Congratulations on your offers - you're in a great position, with two excellent programs from which to choose!
Last year, I did the Women's Studies MSt at Oxford, and worked very closely with Anderson and Ghanea, both of whom work on religion (although I'm not sure whether they're involved with the MST Religion course). If the MSt Religion is like the MSt in Women's Studies, you should be able to tailor the Oxford program to your own interests: there are only a few required core courses, within which your work follows your interests, and all written work is for your option courses and (master's) dissertation.
I'd be happy to talk to you about Oxford - PM me if you're interested!