I'm with you in that I've recently left the Church myself. My suggestion would be to not talk about religion for a little while and then introduce points very slowly to your family/friends/readers. Let it slowly add up. Obviously you've done yourself no favors by making a show of your religion in the past, but it happens. If you do it slowly, though, by introducing one point of contention and mentioning curiosity about it, then you have the opportunity to keep doing it slowly, opening the door without much of a creak until it's obvious what's happening and you can step out.

But that's just my suggestion -- I'm not sure that a lot of people around me know I'm agnostic. My mom and grandma know on the surface, and my dad knows I'm "questioning", but it's really only my close friends that know I'm full-on agnostic. Thus, maybe I'm not the best source, but at the same time I was raised in a somewhat religious but not uber-religious setting.