I've heard that Pascal's Wager is the atheist's nightmare. Actually, it's a gift to atheists.
It turns out it's hard to explain Pascal's idea without it sounding silly. Like this: "It's better to believe in a god that doesn't exist than to disbelieve in a god that does." Not mocking, but that just sounds comical.
Here is the most compelling version: "A rational person should live as though God exists and win infinite joy. If God does not actually exist, such a person will have only a finite loss."