I do an experiment from time to time, I love walking around a store or the mall, and simply smiling at people. It is funny to see the reaction on most peoples faces. I don't recall a single person ever getting mad or offended, but I can remember hundreds of smiles in return. Try it sometime, simply smile at someone when you are sitting at a red light, or when you are waiting in line at the grocery store (be sure it is not a creepy "I am a weirdo" smile, but just a simple smile), and watch what happens. You don't even have to say anything, just smile, and I bet you will get a smile in return!
Wouldn't the world be just a little nicer if we all went around smiling at each other? Oh, and by the way, it works at church too!