Many atheists I know grew up practicing the religion of their parents. It’s a typical method of indoctrination. Your parents believe something (i.e. Jesus) and they want you to believe it.
Of course, religious parents want their kids to think on their own as well. They don’t see themselves as “indoctrinating” their kids. But they obviously have an influence on them and inevitably, the kids will imitate their parents.
When many atheists have children, they want to do something different. They don’t want their kids to automatically become atheists simply because the parents don’t believe in a god. Instead, they would like to give the kids tools to think on their own. Hopefully then, the children will decide what to believe when they’re old enough to think about it.
Dale McGowan explains in his new video:
For me, the key part begins at the 6:12 mark but the whole video is worth checking out.
And the plea to religious parents to act in a similar way is fantastic. I wonder how many of them do that sort of thing.