Maybe the reason they appear to be ex-fundamentalist, is because they’re always attacking the easiest target; Biblical literalism.

John

1.) I think Sam Harris offered a good explanation in his book “The End of Faith”.

2.) Two reasons: One, because the rationality of a belief, and the rationality of those who articulate the belief, are not always synonymous. As a Christian, you may appreciate the point simply by perusing the site Fundies Say the Darndest Things.

Second, I think it’s a matter of perspective. I’ve debated Christians for a while and found many of their arguments to be void of sound reasoning, and been told the same.

3.) If I understand the question right, you’re wondering why the atheists you encounter appear to have been converted from fundamentalist Christianity. I don’t have an answer, because the atheists I encounter frequently on discussion forums and blogs don’t seem to have much of a fundamentalist mindset to me.