Lya Kahlo did an informal study of Christian forums, visiting them and openly announcing her atheism to see what would happen. She visited 35 different forums. 7 banned her because she was an atheist, 28 continued to welcome her. She was accused of trying to corrupt the young and repeatedly asked “if you don’t believe in God, why care about anything?” (17 times).

She lists the ten most common misconceptions about atheists at the forums she visited:

1. Atheists hate god/are jealous of theists
2. Atheists are arrogant and don’t want anything “superior” to them
3. Atheists have never experienece religion
4. Atheists have never read/don’t understand the bible
5. Atheists just don’t want to receive the truth
6. Atheists are bitter/angry
7. Atheists just don’t want to admit they sin
8. All atheists support abortion/evolution/liberal politics/communism/fascism/etc
9. Atheists are gay
10. Atheists want to destroy/limit religion

And five most common excuses for not having evidence of the existence of God:

1. god doesn’t need to prove himself to his creations
2. the bible says {insert nonsense here}
3. the evidence is all around us – (meaning existence is proof of god)
4. Faith is all we need
5. Pascal’s Wager

She also gives a list of the most common fallacies she saw used (14 of them) and the four most common hoaxes/forgeries given as evidence.

It would be interesting to see someone perform the reverse experiment, though there are a lot fewer atheist forums to choose from. I suspect the Internet Infidels Discussion Boards would come out favorably by comparison, though I have no doubt examples of fallacious argument would still be easy to come by in any unmoderated forum.

(Hat tip to Pharyngula.)