You're arguing presuppositions, namely the existence of God. However, if you were to read up on the matter, you'll find that study has been done on some religious diets, and for it's time and culture, the Kosher diet makes a lot of sense scientifically to keep people healthy and decrease the risk of disease. It's pretty remarkable, really. Even now, many Jews who have rejected all notions of there being a god still follow the dietary guidelines in the Torah. Why? Probably because they are decent guidelines. I'm not Jewish and do not follow kosher, halal, or any other religious diets, but they have their backing.
This isn't a thread to discus religion (though it's been used to discuss pretty much anything) so I'm going to leave it at that. But one popular thing I hate is the idea that because something is religious, it has no basis in reality and isn't a rational option. There are some religions, and sects of religions that are that way, but there are also some incredibly intelligent people who are religious and have very well thought out beliefs on the matter. Organized religion is a tool, and like a lot of tools, it can be used to bash someones skull in, or feed millions. I've seen it used both ways.