I use pretty much the same technique as Rick described, for about the same reasons. I am an advocate of polite but firm. You have to expect to SAY NO TWICE.

1. Can I tell you about xxxxxxxx?
Me: No thank you, I'm not interested?

2. Would you care to tell me why you don't want (your soul saved, to save money, etc.)
Me: No, I wouldn't, thank you. Have a nice day. Bye!

This approach has only once ever failed to result in a polite disengagement. She was screaming at me as I hung up that it wasn't fair, I hadn't given her a chance...yadda yadda yadda.

Click.

W-O