If the social evil of letting atheists have and raise children is allowed, they'll be raised in deviance, perversion, and inferiority.
Likely learning that pedophilia or sex with animals are just another "lifestyle choice", rather than inherantly revolting, among other vile and atheistic traits, such as distain for intellectualism, virtue, and higher things in favor of the beastly and material things which the sub-human atheist lusts over, whether it be rape, bestiality, child molestation, or other natural traits and habits of the atheistic.
Based on this, I'd argue that the state should mandatorily confiscate the children from all atheistic homes in America and Western Europe, perhaps transferring them to Catholic or other religious boarding schools, where they will be taught and indoctrinated into virtue, intellect, civilization and higher-value things, rather than pedophilia, rape, bestiality, sodomy pornography and other nastly little vices which the atheist naturally favors over virtues, as would be naturally expected of any other feral beast or vermin which lacks any redeeming trait worthy of being called "human" to begin with.
Perhaps even a 0-child policy which specifically profiles atheists and other moral, intellectual, and aesthetic degenerates, even if this involves mandatory or forced abortion, it would arguably be the lesser evil than allowing the atheist to breed, would it not?
(If I had the power to, I'd personally eliminate every atheist on the planet, sadly I don't, so all I can do is do everything humanly possible to marginalize them and make sure they're socially regarded in the same category as serial killers, pedophiles, and rapists, given that such things are merely the very practice of atheism to begin with, and any atheist who doesn't rape, murder, torture children and such isn't being a very good atheist at all, now is he?)