There have been a few questions about how to handle door-to-door god solicitors....this is how I handled mine today.
"knock knock"
Yes?
Hi! We'd like to talk to you about some good news! We see you probably are busy (I'm in my robe and hair wrap), so we'll leave you alone.
Thanks.
But we can come back!
Please don't. I'm atheist and prefer you don't come back.
Okay, we'll make note of it.

See? Quick, painless, and not a bit hostile or disrespectful. The icing on the cake? I live across from my apartment building's office. Just as I was about to call about the solicitation policy, the manager and assistant manager come out, and very nicely let them know they can't solicit. She even gives them a business card! It was classy!!