Come on guys, not in church!
I'm warning you, don't mess with Sr. Molotov.
It's hard to know how your child will react, largely because of the difficulty of seeing the world through six-year-old windows in that boy's head (if he's six, whatever age). That crap about needing church so that one can understand western civilization is horseshit--by the time one has sufficient intellectual sophistication to understand western civilization in a meaningful way, one is likely to have already decided upon religion.
My parents were Catholic (father born, mother a convert, and therefore a fanatic). I was raised by my grandparents (grandfather a lapsed Catholic because his daddy hated the priest and stopped attending; grandmother a Methodist raised by her Presbyterian mother, and no, i don't know how that one came about). They were, however, believers in the notion that one respected the religious beliefs of others, so we were raised as Catholics, by god, right now, whether you like it or not!
I didn't like it. I recall vividly my reactions, from a very early age. When i was five, my best buddy and i were goofing around in the back of the church during catechism, and the nun came down on us like a ton of bricks. She beat the crap out of us, while making repeat the lesson for the day: "Who made you?" "God made me." "Why did god make you?" "To know him and love him in heaven." It sure as hell didn't feel like love to me.
So what i recall from a very early age is resentment at what was being foisted on me. I understand that this is not likely to be your tack, but i am trying to get across to you that you may well not know how your sprout will react to church. I suspect that with you, if he does get involved in a church, it will be because of his social contacts, that he will do it for social reasons--just as you did yourself. I don't think that there is any inherent intellectual value, no value of maturation to be derived from participation in organized religion. If he wants to play, let him. If he wants to quit, let him do that too. I'd say, answer his questions as truthfully as possible, including what you believe or don't believe and why--he'll make up his own mind. I feel you give the kid a good home and that even if he turns into a holy roller, he'll be a fairly intelligent and well-adjusted holy roller (which makes me suspect that he'll never be a holy roller, but you never know).
By the way, Arthur Schlesinger Sr., not the one you're thinking of, but his pappy, made his name as an historian doing the pre-revolutionary colonial period in America. He estimated that at least half, and possibly more, of the colonial population were un-churched. Kinda shoots in the ass all the propaganda about early Americans being devout religious believers who came here looking for freedom of worship. Actually, many of those who were devout were looking for the freedom to erect religious establishments of their own where they could lord it over everyone else, and impose a "my way or the highway" program on everyone who fell afoul of their fanaticism.
...I'd say, answer his questions as truthfully as possible, including what you believe or don't believe and why--he'll make up his own mind...
I'll check the "Strongly Agree" box.
Also answer questions about what others believe and why.
This is true of the "churched" as well as the "unchurched".
I love the word "churched", by the way.