Ooo the "The Bible was written by God" argument! I love that one!
All the Bible is is circular logic. I can do circular logic too. Watch.
God didn't write the Bible. Why? Because the Bible isn't perfect. Why isn't the Bible perfect? Because it was written by people, who are imperfect. But God wrote the Bible! Therefore God is imperfect! But god can't be imperfect. Therefore god doesn't exist and the Bible is a load of ****!
Sarcasm does tend to make people go on the defensive and back up.