#1? Really?
I can't speak for everyone else, and it's clear that not every ex-JW becomes an atheist. It certainly doesn't help to have had the Bible rubbed in my face all my life, but some see through it regardless. In point of fact, I did try to observe the meetings with a loose, liberal, metaphorical understanding of Christian doctrine. I found it impossible in that setting, though the Unitarian Universalists seem to accept atheism and metaphorical understanding just fine.
I'm atheist because I have looked at where these beliefs come from, how we evolved, and how they evolved right along with us. It's theology and anthropology. So, humanism, really.
I respect another person's right to fantastical beliefs, and I acknowledge the role of religion in politics. It's not going away anytime soon. This is why I have come to prefer street epistemology and the Socratic method rather than blunt, aggressive assertion.
But I am curious. Who says that Jehovah's witnesses produce more atheists than any other religion or sect?