i myself am an atheist in a religious family and the best advice I can give u is keep it lowkey. People will snitch on you if you tell them. Also u can pretend ur religious in front of them and do the fuck u want elsewere. you gain more by pretending to be religious and staying in the in group then leaving it because religion despite its stupidity is good at bringing people and communities together and you dont want to make urself an outcast.