As regular readers of my blog know, I have two children, a son who is six and a half and a daughter who will turn 5 next week.
Thus far, the topic of religion has not come up much between us. The biggest thing I have done is tell them that when they say the Pledge of Allegiance, that they can skip the "under God" part. Whether or not they actually do in school I don't know, nor do I quiz them about it.
Both of my children know what a church is, having attended and/or participated in several weddings in Catholic churches. Not far from where we live there is a big Korean church and a couple of Hebrew schools (Plainview has a large Jewish population), all of which have childrens playgrounds in them. Whenever I would drive past them with my kids in the car, they would call out "Daddy, I want to play in that playground." I would reply to them that they can't, because they are not Korean kids or Jewish kids. A couple of times, my son would say "I want to be a Jewish kid." I got a good laugh out of that.
The most I discussed with them about the idea of god is that I told them that some people believe there is someone up in the sky called God, but that daddy does not believe that such a being exists. Apart from that though, I really have not made any effort to put an atheist stamp on them. I want to wait until they are older to be able to understand the matter better, and I want them to make their own choices.
I would be interested though how any other parents here in the atheist blogosphere handled the subject of religion with their children, and at what age did they discuss it with them.