Works like this:
|-------|--------------|-------------|
| | Belief | Non-Belief |
|------ |--------------|-------------|
| Right |Go To Heaven | no loss |
| |Big Gain | |
|-------|--------------|-------------|
| Wrong |Small Loss |10 Die |
| | (some time) |20 GOTO Hell |
|-------|--------------|-------------|
So, you basically may lose a trifle amount of time in religious services if you're wrong about believing God exists, but you have a lot to gain if you're right, which, if you were a gambling type, it would make more sense to bet on God existing, because that comes with the biggest pay off.
Initally, this was offered as an initial motivation for a person to join the Church, and later it was supported by internal Dogma. This was the First Step, so to speak.