marXian

I defended my dissertation last April (2019). I used Scrivener to write my diss and then exported it to Word for my committee and when it was time to submit to ProQuest. 
Advantages I saw in Scrivener:
- I found it really easy to keep everything organized. Some of what you can do with Scrivener I'm sure you can do with Word. But I thought the layout of Scrivener was really easy to use. You can keep a menu open on the left that lists each section/chapter of your diss. However you want to break it down. Then what shows up in the writing window is whatever chapter you have selected. So you can flip back and forth between chapters really easily, re-order them really easily (if necessary), etc. This also allows you to very quickly keep track of any stats/targets that you need to keep track of (e.g. word count targets or restrictions you set for yourself, etc.)
- FOOTNOTES. Scrivener keeps your footnotes listed on the lefthand side of the window making it very easy to find the notes you're looking for. I honestly never used Endnote or any footnote tracker because everything can be done in Scrivener. As long as you import/enter your bibliographic info as you go along, Scrivener does a very good job of keeping everything organized.
- Scrivener has a "cork board" feature where you can "pin" notes to yourself, reminders, etc. It's basically a separate tab like the chapters that can be pulled up just be clicking on it. I found that much easier to use than a running list of notes in a Word doc (which I still had) or even a physical board. It also has a comments feature that's much easier to use than in Word.
Drawbacks:
- The major issue was exporting to Word sucked. I used Turabian citation style, but Scrivener doesn't have that as an option. Chicago is obviously very close, but even then, the export didn't get the formatting exactly right. The main thing was that all the footnote numbers were superscript and not indented at all. So when I did my final export for my committee before my defense, I had to go through and fix the numbers on 400+ footnotes. It didn't take as long as it sounds it might, but it was still annoying. Had to do it again after I cleaned it up for ProQuest.
I'm starting a new book project now, and I've gone right back to Scrivener.  

In my opinion, this is the time to overhaul PhD programs in the field. Even before the pandemic few of us were getting tenure-track jobs. Nowadays--and I suspect this won't change much in the next five years, if ever completely revert to pre-pandemic times--basically no one is getting a job. telkanuru is right on both accounts. Top programs are not dealing with reality, at least the reality facing nearly all PhD grads, no matter program ranking. These programs exist in institutions with excess. And I can't really blame those departments. If I was faculty at UVA I would be happy to continue on the way things have been for decades, regardless of whether tenure-track jobs have trickled to nearly zero. I would also be happy, as all R1 departments are right now, to train my doctoral students for jobs that don't exist and to continue enforcing the idea that a PhD in religion/et sim. is only meant--only really matters--if it prepares you for those jobs that no longer exist. 

Even if you rate yourself a workaholic, I'd never encourage someone to take more than three courses their first semester. The work expected of you is going to be higher than as a M* student. On top of that, and this is school dependent, but you're going to be encouraged to take on administrative responsibilities too - sitting on a committee (mostly), and probably other small things. All of this is in addition to balancing social and personal responsibilities.
Start at three and see how you feel in the spring. Keep in mind though that as you get settled into the program they tend to ask more of you.

Thank you so much for this response @marXian! My professors and advisors have certainly been candid about the state of the job market, and I'll definitely be pursuing/relying on funding moving forward. It took me forever to figure out what I actually wanted to do, so I'm hoping the future headaches will all be worthwhile to be in a field I really like.

Hey there, I recently finished my Ph.D. (Northwestern, 2019) in roughly your area of interest (phil of religion) and have some thoughts.
First, I'm not going to tell you not to pursue this based on how bad the job market is. Other people here will. But people told me the same thing 10 years ago when I was first looking at Ph.D. programs. If you're an RS major and you've had any conversations at all with faculty mentors about grad school, I'm sure (I hope) they told you this. It's really, really, really hard out there. I don't pretend to know what it will be like 6-10 years from now, but chances are it still won't be great. That doesn't mean it's a bad idea to pursue grad school, but you must go in with eyes wide open. I applied to over 80 jobs last year while I was finishing my dissertation, preparing for defense, and then after I defended. I was really lucky to get a full time teaching job, but it literally fell out of the sky a week or so before I was going to start applying to retail jobs, and it's at a community college on the other side of the country from where my family and my wife's family are from. We're okay with this, but some people would not be. You have to weigh all of this. Go in fully aware that the chances are stacked against you for getting even a full time gig at a community college.
Second, don't pay a single dime for grad school. Unless you're independently wealthy, taking out loans to attend an MA program is just a bad idea (an even worse idea for a Ph.D.) You can find well-funded MA programs and certainly any Ph.D. program that's going to position you for a job is going to have funding.
That said...
You're right that it's difficult to get into a PhD program straight from undergrad, but given your fields of interest, not impossible. I had two colleagues in my cohort (2012) who came straight from undergrad, one in each of the fields you're interested in. Honestly, you sound like a competitive undergraduate candidate. Depending on the program, if the fit is really good and you have a compelling project, I definitely think you have a shot.
I do also think, however, that a funded MA will help you immensely in clarifying your interests and getting connected to the right people. In American Religion, I think this is especially important. Florida State has an excellent MA program with a great Ph.D. placement record and is especially strong in American Religion. Obviously places like Harvard and Yale would be well suited for either interest. 
The most important thing for a PhD application is "fit" which is an ambiguous, frustrating term that's really hard to quantify. Basically, the adcom has to "feel" that you would work well given the resources of the department and the broader university. Sometimes it may seem like you are an amazing fit for a particular department but you get rejected outright (I felt this way about UVA--didn't even get waitlisted) and sometimes you might be surprised by a department thinking you're a good fit (I applied to NU at the last minute and did not think I had any chance). This is one reason why attending a "well-connected" MA program where faculty know other faculty in good PhD programs is helpful because they can potentially steer you in the right direction. 
For MA applications, you're likely a very strong candidate at any MA program in the country. The divinity school programs are much easier to get into (typically) than a traditionally funded MA program (e.g. FSU, Miami OH, etc.) in part because a lot of students pay a lot of money to attend those programs. There's usually aid available at the higher tier programs (Chicago, Yale, Harvard, Duke, etc.) but they're not going to pay you a stipend or anything like that. At a place like FSU, you're going to get a modest stipend on top of a tuition waiver in exchange for TA work.
In short, yes, you definitely need to start working on a personal statement/statement of purpose now, at least for Ph.D. applications.
Hope that's helpful!

Hey there, I recently finished my Ph.D. (Northwestern, 2019) in roughly your area of interest (phil of religion) and have some thoughts.
First, I'm not going to tell you not to pursue this based on how bad the job market is. Other people here will. But people told me the same thing 10 years ago when I was first looking at Ph.D. programs. If you're an RS major and you've had any conversations at all with faculty mentors about grad school, I'm sure (I hope) they told you this. It's really, really, really hard out there. I don't pretend to know what it will be like 6-10 years from now, but chances are it still won't be great. That doesn't mean it's a bad idea to pursue grad school, but you must go in with eyes wide open. I applied to over 80 jobs last year while I was finishing my dissertation, preparing for defense, and then after I defended. I was really lucky to get a full time teaching job, but it literally fell out of the sky a week or so before I was going to start applying to retail jobs, and it's at a community college on the other side of the country from where my family and my wife's family are from. We're okay with this, but some people would not be. You have to weigh all of this. Go in fully aware that the chances are stacked against you for getting even a full time gig at a community college.
Second, don't pay a single dime for grad school. Unless you're independently wealthy, taking out loans to attend an MA program is just a bad idea (an even worse idea for a Ph.D.) You can find well-funded MA programs and certainly any Ph.D. program that's going to position you for a job is going to have funding.
That said...
You're right that it's difficult to get into a PhD program straight from undergrad, but given your fields of interest, not impossible. I had two colleagues in my cohort (2012) who came straight from undergrad, one in each of the fields you're interested in. Honestly, you sound like a competitive undergraduate candidate. Depending on the program, if the fit is really good and you have a compelling project, I definitely think you have a shot.
I do also think, however, that a funded MA will help you immensely in clarifying your interests and getting connected to the right people. In American Religion, I think this is especially important. Florida State has an excellent MA program with a great Ph.D. placement record and is especially strong in American Religion. Obviously places like Harvard and Yale would be well suited for either interest. 
The most important thing for a PhD application is "fit" which is an ambiguous, frustrating term that's really hard to quantify. Basically, the adcom has to "feel" that you would work well given the resources of the department and the broader university. Sometimes it may seem like you are an amazing fit for a particular department but you get rejected outright (I felt this way about UVA--didn't even get waitlisted) and sometimes you might be surprised by a department thinking you're a good fit (I applied to NU at the last minute and did not think I had any chance). This is one reason why attending a "well-connected" MA program where faculty know other faculty in good PhD programs is helpful because they can potentially steer you in the right direction. 
For MA applications, you're likely a very strong candidate at any MA program in the country. The divinity school programs are much easier to get into (typically) than a traditionally funded MA program (e.g. FSU, Miami OH, etc.) in part because a lot of students pay a lot of money to attend those programs. There's usually aid available at the higher tier programs (Chicago, Yale, Harvard, Duke, etc.) but they're not going to pay you a stipend or anything like that. At a place like FSU, you're going to get a modest stipend on top of a tuition waiver in exchange for TA work.
In short, yes, you definitely need to start working on a personal statement/statement of purpose now, at least for Ph.D. applications.
Hope that's helpful!

Haven't read much about this program. You're using OSX I assume?

@marXian, glad to hear this! I just finished exams and have been pondering downloading Scrivener as I begin the dissertation process. 

I defended my dissertation last April (2019). I used Scrivener to write my diss and then exported it to Word for my committee and when it was time to submit to ProQuest. 
Advantages I saw in Scrivener:
- I found it really easy to keep everything organized. Some of what you can do with Scrivener I'm sure you can do with Word. But I thought the layout of Scrivener was really easy to use. You can keep a menu open on the left that lists each section/chapter of your diss. However you want to break it down. Then what shows up in the writing window is whatever chapter you have selected. So you can flip back and forth between chapters really easily, re-order them really easily (if necessary), etc. This also allows you to very quickly keep track of any stats/targets that you need to keep track of (e.g. word count targets or restrictions you set for yourself, etc.)
- FOOTNOTES. Scrivener keeps your footnotes listed on the lefthand side of the window making it very easy to find the notes you're looking for. I honestly never used Endnote or any footnote tracker because everything can be done in Scrivener. As long as you import/enter your bibliographic info as you go along, Scrivener does a very good job of keeping everything organized.
- Scrivener has a "cork board" feature where you can "pin" notes to yourself, reminders, etc. It's basically a separate tab like the chapters that can be pulled up just be clicking on it. I found that much easier to use than a running list of notes in a Word doc (which I still had) or even a physical board. It also has a comments feature that's much easier to use than in Word.
Drawbacks:
- The major issue was exporting to Word sucked. I used Turabian citation style, but Scrivener doesn't have that as an option. Chicago is obviously very close, but even then, the export didn't get the formatting exactly right. The main thing was that all the footnote numbers were superscript and not indented at all. So when I did my final export for my committee before my defense, I had to go through and fix the numbers on 400+ footnotes. It didn't take as long as it sounds it might, but it was still annoying. Had to do it again after I cleaned it up for ProQuest.
I'm starting a new book project now, and I've gone right back to Scrivener.  

I defended my dissertation last April (2019). I used Scrivener to write my diss and then exported it to Word for my committee and when it was time to submit to ProQuest. 
Advantages I saw in Scrivener:
- I found it really easy to keep everything organized. Some of what you can do with Scrivener I'm sure you can do with Word. But I thought the layout of Scrivener was really easy to use. You can keep a menu open on the left that lists each section/chapter of your diss. However you want to break it down. Then what shows up in the writing window is whatever chapter you have selected. So you can flip back and forth between chapters really easily, re-order them really easily (if necessary), etc. This also allows you to very quickly keep track of any stats/targets that you need to keep track of (e.g. word count targets or restrictions you set for yourself, etc.)
- FOOTNOTES. Scrivener keeps your footnotes listed on the lefthand side of the window making it very easy to find the notes you're looking for. I honestly never used Endnote or any footnote tracker because everything can be done in Scrivener. As long as you import/enter your bibliographic info as you go along, Scrivener does a very good job of keeping everything organized.
- Scrivener has a "cork board" feature where you can "pin" notes to yourself, reminders, etc. It's basically a separate tab like the chapters that can be pulled up just be clicking on it. I found that much easier to use than a running list of notes in a Word doc (which I still had) or even a physical board. It also has a comments feature that's much easier to use than in Word.
Drawbacks:
- The major issue was exporting to Word sucked. I used Turabian citation style, but Scrivener doesn't have that as an option. Chicago is obviously very close, but even then, the export didn't get the formatting exactly right. The main thing was that all the footnote numbers were superscript and not indented at all. So when I did my final export for my committee before my defense, I had to go through and fix the numbers on 400+ footnotes. It didn't take as long as it sounds it might, but it was still annoying. Had to do it again after I cleaned it up for ProQuest.
I'm starting a new book project now, and I've gone right back to Scrivener.  

Yes! It turned out I didn't have to languish on the wait list too long; I just got the email that I was accepted to my No. 1 choice (FSU)! Now I'm all shaky ... having trouble processing that this is actually happening.

Analytic/continental is not really a meaningful distinction in Religious Studies programs. The vast majority of RS scholars doing politics/social theory/ethics/etc. engage continental philosophy as it is utilized as "theory" broadly speaking. But many folks are not reading the primary source philosophers on which theory is based. Many RS scholars have not read, for example, Foucault, Deleuze, or Agamben but instead receive these figures through others who have read them and formed their own theories related to religion, e.g. Talal Asad. Even when you do encounter people who have read these figures, their understanding of them seems to be somewhat idiosyncratic, at least with respect to how philosophy/literature/theology programs engage them.

Of the programs you listed, Northwestern and (I think) Indiana regularly admit people straight from undergrad. I just graduated from Northwestern's program, and there were two people in my cohort who came in straight from undergrad. I've known plenty of others as well.
That said, if you're really serious about American Religions, I would absolutely consider taking an MA first at FSU or Miami (OH) or another program with an extremely strong track record in that subfield. You'll have a much, much better shot at top AmRel Ph.D. programs with an MA. And, to clarify xypathos' point about being put in an MA program--not a lot of elite Ph.D. programs have a terminal MA to put you in. Northwestern definitely doesn't. Neither do the Ivies you listed. And schools that do, like Columbia or UChicago, will make you pay a ton of money for theirs with no promise of Ph.D. admission when you're done. I would highly recommend seeking out funded MA programs like FSU and Miami where you'll get some teaching experience and you'll work with really well-respected scholars in the field.

@PonderingPerson400 I just finished my Ph.D. in religious studies and my subfields are philosophy of religion/theology/social philosophy. You can PM me if you want some more detail, but let me throw some things out to consider.
First, you ought to look at the kinds of jobs that are out there. Things will almost certainly change by the time you're in my position, which, realistically, could be nearly a decade if you pursue an M* degree before your Ph.D. I took 6+ years, which was the norm for my cohort (we all defended within about two months of each other.) Still, it's helpful to see the kinds of jobs that are out there for someone with an MTS and a Ph.D. with a dissertation broadly in philosophy of religion and/or theology. This is where you want to look: https://academicjobs.wikia.org/wiki/Religious_Studies_and_Theology_2018-2019
I'd recommend anyone thinking about a Ph.D. in RS to look through this year's job opportunities. There were actually a decent number of jobs for people in phil of religion/theology both this year and last year. Here's the thing though: You'll notice how many of these jobs are at Catholic schools. That doesn't preclude non-Catholics from applying to them, but some are very clear that they want someone with an expertise in Catholic systematics/moral theology/social teaching/etc. specifically. Note also that some schools are places like Calvin College and George Fox--both evangelical schools. I only point that out to say that some of these theology/philosophy jobs require a significant amount of finesse if the school happens to be more conservative than you are. I had to spin my dissertation research, which is about the relationship between normativity and history in theology from the perspective of German philosophy of history/religion, for each of these schools I applied to. Finally, you'll note that some of these postings are looking for someone with expertise in African American theology, gender/sexuality, etc. I would strongly recommend adding an emphasis like that to your work to open up those kinds of opportunities. 
Second, tenure track jobs are extremely hard to come by. There is a great deal of luck and chance involved--even more so than Ph.D. admissions. If you think about it, that makes sense. If you've finished a Ph.D. program at a reputable school, chances are you are eminently qualified to take a teaching position at a university. No not everyone's research is world-changing or even good, but it was good enough to earn a Ph.D. which means it's probably pretty good. You could say that at least 90% of people coming out of top programs are more than qualified for a TT job. That's obviously not true for Ph.D. admissions, where anyone who can pay for the application can apply. People who have no business applying to Ph.D. programs do all the time. That's not true of the job market (at least not nearly to as great a degree). The vast majority of people have done the work: they've earned the degree, they've published, they're part of professional organizations in one way or another, they've won major grants, they've done 20+ drafts of all their materials, etc. 
I know people who are brilliant scholars who bounced around from temporary position to temporary position for 5-7 years before finally landing a tenure track job. I'm talking about people who have contributed significantly to the field, published at least one book and multiple articles, sit on editorial boards of journals and steering committees of AAR program units. Even those kinds of people can struggle to find a job. On the other side of the coin, I've known a few colleagues from my program who landed a TT job before even defending their dissertation. They're fine scholars, but nowhere near the caliber of the first group. They just happened across the right job at the right time. 
Because of that, if you're dead set on a Ph.D., back up options for a university teaching job are really important to begin thinking about even now. Normally, I would strongly recommend against an MDiv, simply because you have to do a lot of "fluff" that likely isn't going to be relevant to your academic work. BUT if you are already firmly committed to a denomination and could see yourself going into ministry as an alternative to a TT job, then I would actually do the MDiv. While I can't exactly say that I regret not pursuing an MDiv, I do kinda wish I had that in my back pocket right now because I think it would make me a more attractive candidate to churches and would open more options for the kinds of church jobs I could apply to. For example, I'm unlikely to land a solo pastor gig somewhere unless it's a nondenominational church that doesn't care about an MDiv. But I'm also very unlikely to be considered by a nondenominational church since they tend to be hyper conservative and somewhat anti-intellectual. They're going to look upon someone with two MAs and a PhD from a "secular" school with extreme suspicion. So the MDiv would really be helpful because a lot of more liberal denominations want to hire people who are willing to pursue ordination, which I probably can't do because I don't have an MDiv.
That isn't to say that ministry is the only backup option. I've been applying to a wide range of jobs that have nothing to do with ministry. So in an ideal world, I would say doing an MTS or, perhaps better, an MA in Chicago's philosophy of religion program (or Yale's MARc) is going to give you the best leg up for getting into a Ph.D. program in religious studies to do something philosophy of religion related.
Like I said, feel free to PM me if you have any follow up questions.

You can demonstrate your potential by talking about your research interests and plans in the Personal Statement. You don't have to be as focused as you would be for a Ph.D. application, but you can still say what interests you about Islamic studies more specifically--i.e. what aspect of Islam you want to study. Again, don't talk about why you're interested in Islamic Studies. Talk about what you want to research. If that's written well and comes across as interesting and promising to the admissions committee, they'll be much more likely to overlook the GPAs.

I know it feels difficult to hear tough advice, but I genuinely wish someone had given me advice like that before embarking on graduate school. I'm in my tenth year of college with this year only being my first year of PhD work (4 year undergrad, 3 year MA, 2 year MTS). It's a super long and difficult road. 

In addition to the programs mentioned, also look at Drew and Villanova. Villanova has both a theology department and a philosophy program with a theological track. 

To the OP, I just want to reiterate that xypathos is correct that you're not going to get into a philosophy Ph.D program with an M* degree in theology, no matter how philosophical the degree is. Philosophy programs are notoriously protective of "philosophy-as-such," whatever that means, and so typically do not admit anyone they deem to have strayed from that path. 
I work in your field, broadly speaking (continental philosophy of religion), and I think you might consider taking another M* degree both to try and raise your GPA but also to demonstrate that you do philosophy if you really want to get into a philosophy program. UChicago's philosophy of religion program would give you a much, much better chance if added to your credentials. Since they have an internal petition process for MA students to be considered for the Ph.D program, it would greatly increase your chances there as well. 
If you're interested in other religious studies programs besides UVA, I would look into UC Santa Barbara (Tom Carlson), Syracuse, Columbia, and Stanford, although those last two admit philosophy of religion folks only very rarely. The other issue you're going to face (and I know because I faced it as well) is making your project as non-theological as you can. You've situated yourself in a somewhat difficult practical position: Too philosophical for theology programs, too theological for philosophy/RS programs. That's not necessarily a bad thing from a career perspective down the line. Not to toot my own horn, but I feel I've been able to carve out a niche for myself in the AAR and have caught some moderate attention of other scholars whom I respect and have now started to collaborate with. As far as the job market is concerned, it remains to be seen if I'll have any success, but I feel comfortable applying to positions in theology, philosophy of religion (in an RS department), and religious studies (e.g. looking for an expert in Christianity.)
But to get into an RS or philosophy program, you have to sell yourself as doing something that doesn't have theology as the primary focus, even if you engage theological texts. I think completing another MA in a program like UChicago will really help you do that.

@wilsonrg With all due respect, xypathos is not only very respected on the board, but moreover and to the more germane point, his response provided answers that were spot on and lucid. Perhaps it was not in the tone or inflection you desired, they were nonetheless entirely accurate. A tad bit of advice and counsel, the academy is a long arduous road, filled with much more disappointment than success, and if this blunt but totally on point assessment already rankles you, perhaps you need to rethink your attitude as you go down this incredibly long path....

Your second point needs a modification. The programs are shorter not necessarily for the reasons you state but mostly because there is no coursework and no qualifying/comprehensive exams in these programs. You're just researching and writing the dissertation. The lack of coursework/exams is also one of the primary reasons it's difficult to get a tenure track job in the U.S. from a U.K. program. U.S. departments don't trust that U.K. programs produce thoroughly trained scholars who are prepared to teach a wide range of undergraduate and/or graduate courses. Courses/exams don't guarantee that, but they make it more likely. That's not to say there aren't great scholars with U.K. Ph.Ds--but they've had to prove themselves through publishing.
One more thing: The lack of oversight and support, arguably, makes the dissertation process actually a bit longer than it would be in a U.S. institution, where someone writing a dissertation in theology/philosophy of religion, usually takes ~18-24 months start to finish for the dissertation give or take 6 months. A diss requiring substantial archival research or field work could take a bit longer, but I think about 24 months is probably the average in religious studies.

Your second point needs a modification. The programs are shorter not necessarily for the reasons you state but mostly because there is no coursework and no qualifying/comprehensive exams in these programs. You're just researching and writing the dissertation. The lack of coursework/exams is also one of the primary reasons it's difficult to get a tenure track job in the U.S. from a U.K. program. U.S. departments don't trust that U.K. programs produce thoroughly trained scholars who are prepared to teach a wide range of undergraduate and/or graduate courses. Courses/exams don't guarantee that, but they make it more likely. That's not to say there aren't great scholars with U.K. Ph.Ds--but they've had to prove themselves through publishing.
One more thing: The lack of oversight and support, arguably, makes the dissertation process actually a bit longer than it would be in a U.S. institution, where someone writing a dissertation in theology/philosophy of religion, usually takes ~18-24 months start to finish for the dissertation give or take 6 months. A diss requiring substantial archival research or field work could take a bit longer, but I think about 24 months is probably the average in religious studies.

I think xypathos is exactly right. A lot of folks have this vision of Ph.D work that they're going to have a really close working relationship with their advisor who is an expert in their field. Having a person who is field-adjacent is actually going to help you better develop as a scholar. The reason is that they can really push you to write more clearly and precisely than someone who is already mired in your field because they need that higher level of clarity to understand your argument. I've found this extremely helpful as I have a terrible habit of always implying my argument through examples rather than coming out and saying it clearly and succinctly.
I work on 19th/20th century German theology, philosophy of history, and social theory (and their intersection). My dissertation is on a relatively little known theologian (little known in the US). I have two co-advisors, one in religious studies and one in philosophy. The RS advisor is a Catholic social ethicist and the philosophy advisor is a Hegel scholar. Both have, at the very least, a passing familiarity with my figure, the philosophy advisor more so than the RS advisor. As I've had some friends and colleagues read over dissertation chapters, people who are intimately familiar with my figure have often missed the places in my dissertation where I'm doing what I describe above. My advisors have not.
Of course, I have had to recruit an expert on my figure to my committee to make sure that my argument makes sense and is contributing meaningfully to the literature (someone from outside my institution). It's also going to be important for her to write me letters for jobs next application season. So having an expert on your committee is definitely a necessity. But that person does not have to be your advisor, and I think it's better if they are not your advisor.

I think xypathos is exactly right. A lot of folks have this vision of Ph.D work that they're going to have a really close working relationship with their advisor who is an expert in their field. Having a person who is field-adjacent is actually going to help you better develop as a scholar. The reason is that they can really push you to write more clearly and precisely than someone who is already mired in your field because they need that higher level of clarity to understand your argument. I've found this extremely helpful as I have a terrible habit of always implying my argument through examples rather than coming out and saying it clearly and succinctly.
I work on 19th/20th century German theology, philosophy of history, and social theory (and their intersection). My dissertation is on a relatively little known theologian (little known in the US). I have two co-advisors, one in religious studies and one in philosophy. The RS advisor is a Catholic social ethicist and the philosophy advisor is a Hegel scholar. Both have, at the very least, a passing familiarity with my figure, the philosophy advisor more so than the RS advisor. As I've had some friends and colleagues read over dissertation chapters, people who are intimately familiar with my figure have often missed the places in my dissertation where I'm doing what I describe above. My advisors have not.
Of course, I have had to recruit an expert on my figure to my committee to make sure that my argument makes sense and is contributing meaningfully to the literature (someone from outside my institution). It's also going to be important for her to write me letters for jobs next application season. So having an expert on your committee is definitely a necessity. But that person does not have to be your advisor, and I think it's better if they are not your advisor.

I think xypathos is exactly right. A lot of folks have this vision of Ph.D work that they're going to have a really close working relationship with their advisor who is an expert in their field. Having a person who is field-adjacent is actually going to help you better develop as a scholar. The reason is that they can really push you to write more clearly and precisely than someone who is already mired in your field because they need that higher level of clarity to understand your argument. I've found this extremely helpful as I have a terrible habit of always implying my argument through examples rather than coming out and saying it clearly and succinctly.
I work on 19th/20th century German theology, philosophy of history, and social theory (and their intersection). My dissertation is on a relatively little known theologian (little known in the US). I have two co-advisors, one in religious studies and one in philosophy. The RS advisor is a Catholic social ethicist and the philosophy advisor is a Hegel scholar. Both have, at the very least, a passing familiarity with my figure, the philosophy advisor more so than the RS advisor. As I've had some friends and colleagues read over dissertation chapters, people who are intimately familiar with my figure have often missed the places in my dissertation where I'm doing what I describe above. My advisors have not.
Of course, I have had to recruit an expert on my figure to my committee to make sure that my argument makes sense and is contributing meaningfully to the literature (someone from outside my institution). It's also going to be important for her to write me letters for jobs next application season. So having an expert on your committee is definitely a necessity. But that person does not have to be your advisor, and I think it's better if they are not your advisor.

Thanks, that's a very helpful way of thinking about it. It'll probably come down to visiting all of them and talking to more folks.