Image: Pascal himself
For more about Pascal's Wager.
Here's what's important if you don't know what's his wager is (from the above Wikipedia link):
It posits that humans all bet with their lives either that God exists or that he does not. Based on the assumption that the stakes are infinite if God exists and that there is at least a small probability that God in fact exists, Pascal argues that a rational person should live as though God exists and seek to believe in God. If God does not actually exist, such a person will have only a finite loss (some pleasures, luxury, etc.), whereas they stand to receive infinite gains (as represented by eternity in Heaven) and avoid infinite losses (eternity in Hell).
There has already been many refutation on this wager but here's one not so rigorous:
-- See that wager? You should do this.
~~ Hmmm.... Tell me, is it worse to not to believe or believe the wrong god?
-- A: believe the wrong one
~~ There are too many gods I don't really know which one to gamble on.
-- B: not believe
~~ Ok So is this some sort of..."whose-commandments-scary-the-most-wins"? I should find the most scary one bye!