Personally, I've been open with my friends and family about my lack of religion and the disdain I have for organized religions in general. I've been that way my whole life, and some people still give me flack for it. I look at such occasions as "teaching moments," when I can help bring a little light into someone else's muddy thinking.

But that's just me. If the question is, what advice would I give to a person that is surrounded by religious influences, and for whom religion makes up a major component of their social support system, then my answer is:

Think what you like, but behave like others.

You glean benefit from your social networks, from your family, from your friends. There is no reason to cast yourself into the role of the "lost sheep" that needs to be helped back on to the path. Continue your living your normal life as you always have. Let your new rationality cast your associations in a new light. Learn what you can, for as long as you can keep your mouth shut.

I would expect that over time, you will naturally start interacting with people that share your new appreciations, and that gradually, the religious folks will fall away slowly as they pursue their own ends.

There's no need to antagonize believers that mean you no harm.