You can find them anywhere, and they say everything. From sexual preferences to your favorite color, there is a bumper sticker to express every idea, personality type, and mood. Your traits, likes and dislikes can be broadcasted via bold and gaudy text to motorists fortunate enough to find themselves behind you in traffic. Whether they like it or not, they will get to know you. Sort of.
Christianity is not excluded from this basic fact of modern life. Whether it be the subtle silver icthus or bold, militant phrases like, "If you died tonight, would you go to hell?", Christians love to plaster indications of their faith on the back of their vehicles. Every once in awhile one will see a minivan, it's rear hatch so thoroughly covered in decals that it begs the question, "are these things addictive?" In my personal experience, these addicts are usually Christians, and their bumper stickers make sure that you know it.
I've never quite understood the thinking behind the Christian bumper sticker. Perhaps it is believed that an aggressive tailgater will read John 3:16 in the middle of rush hour and come to a saving knowledge of the Lord. Maybe the silver plastic "Jesus fish" has a divine property that immediately causes people to believe. Or maybe we're just being bold, showing off our faith to the world and letting them know that we're not ashamed.
But let's be honest. Bumper stickers are about as bold as attending a mass protest; it's easy to be courageous in a crowd of 300 others who agree with you. It's easy to hide behind the tinted glass of a minivan while the person at your back reads, "For all have sinned and fallen short of the glory of God." And personally, I believe they're both equally ineffective in showing God's character to the rest of the world. They're cop outs, plain and simple, and ask little to nothing of us as individuals.
I don't think most people really care what your bumper stickers say. Show me by the way that you live - and by the way that you drive - that you mean it. Don't cut me off in traffic. Don't go twenty below the speed limit. Don't block the entryways to gas stations and fast food joints. Doing these or otherwise driving rudely, when paired with a Christian bumper sticker just makes things worse. Imagine getting cut off in traffic and then immediately being presented with, "IN CASE OF RAPTURE THIS VEHICLE WILL BE UNMANNED." Maybe that's already happened to you.
Bumper stickers are too easy. Loving people? That's hard. But at least it means something.