It depends on the person and the conversation, when religion comes up I mention it then. While I was in college (this being over the last two year) religion came up a lot in sociology, psychology and philosophy classes I was forthright then right away and the instructors were happy to ask me questions and use my expierinces as a kind of live way to interject what kind of effects a cult or strict religion could have on a person.made for interesting conversations.
People will freeze a lot of times when they hear it also, beings how I seem to bring it up when I want a conversation stopped * "in-your-face-religions" can be talk stoppers, for "in-your-face-fanatics"
*no pain intended for truely loving christians