clipped from: atheism.about.com   
Evidence & Doubt
A lot of religious theists don't like being asked directly for evidence to support their claims about gods, angels, miracles, etc. This is curious because in ordinary circumstances, being able to support one's claims is quite basic. Why get defensive about it? One possible reason is that defensiveness is not so much about being asked for evidence, but rather a defending against the doubt which such a request creates. If religious theists were confident, though, a little doubt shouldn't be such a problem, should it?

What sorts of reactions do you encounter when you ask Christians to provide evidence supporting their claims? How do you deal with these reactions yourself? Obviously not every Christian gets defensive when asked for evidence and not every Christian is suddenly confronted with possible doubts simply because they are asked for evidence. It does, however, seem relatively common. What differentiates those Christians who do get defensive from those who don't?