"We’re not Catholics. We don’t have Sunday schools. We don’t indoctrinate our kids “into atheism” from a young age. We don’t have “traditions” to follow. Atheism isn’t attached to any particular cultural identity. Many atheists parents, I gather, encourage their children to think for themselves and not believe in something just because their parents believe it.
We don’t “raise our children as atheists” because that’s forcing our beliefs onto them — and that’s not something many of us want to do.
But damn near every atheist I’ve ever met became an atheist despite his/her parents’ attempts to raise them in a particular religion..." Hemant Mehta, Why Aren’t Atheist Parents Raising Atheist Children?