I know people who honestly and seriously believe fossils were created by the devil and put in the ground to fool us.

At least you understand that you're a heretic for disagreeing with them!

When I graduated from high school, I was a young earth creationist, but by the time I was 30, I had turned 180 degrees, so I hold out hope because I know it is possible for people to change when confronted with the facts. Of course, it didn't hurt that my parents weren't NEARLY as bad as some. We regularly went to places like the Baltimore Science Center, and when I pointed out the discrepancies between that and what I heard in church, their response was fairly ambivalent ("different people think different things, etc"). And they got me a subscription to National Geographic, so when I eventually did become curious about evolution in my 20's, I wen't back through all of those magazines and read every article on the subject. So I didn't have nearly as far to go as some kids.

I have heard the theory that God put fossils in the ground as a test of faith. It's usually either that or some 'they all died in the flood' nonsense.

Ask them why God let Satan get away with putting fossils in the ground to fool us, or why he did it himself.