Adiroth, I kind of agree with your comment:

Sometime you can do a lot more by not doing. You don't have to drag your kids around with you to undoctrinate them, all you need to do is to be a role model for your kids, showing them that an atheist can be a much better person than the religious lot who only feigns morality out of fear of God.

I don't think you even need to be that extreme in your thinking. Just showing them that you're a nice, caring, compassionate person who doesn't believe in a god should do it eventually.

I was brought up with a religious father and non-religious mother, and still have vivid memories (I'm 43 now) of thinking as a child at Sunday School, "but how can we need god to be good - my Mum's one of the nicest people I know and she doesn't have god..something about this isn't quite right". Not long after that, I was politely asked to refrain from attending said Sunday School, because I was asking too many (innocent) difficult questions. Says a lot.