(originally posted as a comment on Friendly Atheist)
I've been thinking about this "used to be an atheist but now I'm in the bosom of Jesus" types. At a risk of raising the "No True Atheist" flag, I don't think they were atheists.
I think they are Apatheists. It wasn't that they didn't believe in god, but they just didn't care. Maybe paid lip service, or attended church with family pressure, but otherwise it was either too hard or too boring or too much to believe, and so by the definition of their old faith, they label themselves as Atheist.
They accept the label, maybe learn some of the ways Atheists act or think, and try that on: in a way, they treat Atheism as if it was a faith, a religion. They read the books other Atheists tell them about, they go to the sites, they nod in appreciation at the witty comments and condemn the god-bothering trolls... but, still, they start to feel something missing still. It doesn't occur to them that the missing thing is them letting go of faith, but rather they start to feel the missing thing being god. They feel that its great to be out of the moral code of their old religion, and for some that freedom means going the other way, over to drinking to excess or sex sex sex. Because they are free now, free from that church they had been in.
And suddenly because a family member makes them or there's a sign or they burn toast and it looks like Jesus; and we have another Atheist turned Christian doing the lecture route. They couldn't keep to their original faith in the first place, and the new one (which could be the old one, but is more likely a revivalist or evangelistic church) isn't boring, they say the right things, couch answers in easy to understand (and wrong) logic. A(pa)theist becomes Theist again.
Apatheism is not atheism.