I have two daughters and a wife who is mildly religious. I think she is afraid to let go of it because here parents are so devout. My dad is a pastor also so there is constant give and take within my family structure. I simply talk to my daughters honestly. My five year old is not old enough to care or ask questions, but my 7 year old is very intelligent and has questioned quite a few things. My wife is very good about not trying to persuade either way(unlike her and my parents) and we seem to have struck a good balance for now. When the questions come I just ask them what they think and try to ensure they understand it is necessary to ask questions and look at all things critically.
"Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind. "