The Wikipedia article on Agnosticism is quite amusing, in the part where it lists all the different shades of agnostic - I particularly liked: "I don't know, and who cares anyway?" and got confused by: "I don't know what you're talking about when you refer to God. Unless we first figure that out, debates over whether god exists are meaningless."
All I'm concerned about is that weirdos, trying to sell me overpriced cheap tea towels, gas/electricity/phone companies, and their religions of choice keep knocking on my door. There's a mailing preference service and a telephone preference service, but not a "go away" preference service. As advised earlier, I'm considering a note similar to the "no junk mail" stickers you can get (however, in the latter case, I keep the recycling box next to the letter box and about 90% of my mail goes straight in) and the same goes for Betterware and Lakeland Plastics as well. So there!