What is wrong with theistic beliefs?

[vulcanlogician]

2) under the spell of an illusion, defined as misinterpreting an actual phenomenon;

I'd say that this is probably the most accurate.

Religion has almost always been the end result of the ignorant misinterpreting their experiences.  Example: people get sick?  It's due to some cosmic force related to the person's exhibited morality.  A demon corrupted them, or karma bit them in the ass, or something else along those lines.

I mean, how many times have we encountered theists who say they believe because of what they've personally experienced - especially if it's something not trivially accounted for?  Despite human psychology dictating that one's individual experience is often faulty at best, due to a variety of factors?  "I know what I experienced.  I know it was real."  Really?  Because physics and psychology tend to say otherwise.

Good point. Now I want to change my answer to illusion. Oh well...