In the clip below, Penn Jillette talks about his bullshit detector:
So I guess my detector on God is that whenever someone uses what they feel as evidence instead of what they think as evidence or what they can prove as evidence, I’m very, very skeptical. The most important thing is to feel about things you feel about — should feel about — and think about things you should think about. You should not feel about the speed of light or evolution and you should not think about love. You should feel “I love you,” you should think about reality. And when someone says they feel the universe was created by a God, that’s nonsense, just like saying, you know, “I’ve thought about it and maybe I should love you.” Don’t mix those two.
(via Atheist Media Blog)