You can learn a lot from bumper stickers. I saw one today that, I believe, is used by pro-abortion supporters. The sticker said "Keep your theology off my biology." Catchy, huh? There were also several budda references and Eastern mysticism stickers. My thought was "without "theology" (ie God), you wouldn't have a biology." People think they can force God out just by saying "I don't believe in you," as if God is an "imaginary friend" that you can wish away. It is sad, but it is a fact of the fallen human nature. Sometimes what people stick on their bumpers (or email signature or whatever) gives you better clues as to who that person is than actually meeting them. I try to avoid stickers myself- I don't want to peel them off later on when they are faded. Plus, if I put a Christian sticker on, then violate a law (regardless of intending to or not), I might cause someone to fall. So my car is boring.
So, what's on your bumper?