Ytaker's Wager
If you worship God you go to heaven. Heaven is so much nicer than hell, so we want to get into it. So the best course is to worship God right?
Wrong. There are many possibilities for worship, and you don't know that God is the one. So you worship many compatible religions instead. I recommend Norse, Greek, Aztec, Roman, and Egyptian.
There were only 25 religions named in a book on my shelves, so if you worship them, from Woden to Isis, you have a five times greater chance of getting into heaven. Logically. This is what logic can get you into eh?
Just in case you're wondering whether they'll mind, remember that Isis was worshiped in Rome almost as soon as they conquered it. They love poly-pantheistic cultures.
P.S. Don't throw facts that you heard vaguely somewhere into your cauldron, and hope for a successful spell to be cast over the readers. Organise it, think about it. Argue against it and see flaws.