Pascal's Wager Definition

noun

An argument according to which belief in God is rational whether or not God exists, since falsely believing that God exists leads to no harm whereas correctly believing that God exists may lead to an eternal reward.

American Heritage

pronoun

(religion) An argument for theism maintaining that belief in God poses less risk if God does not exist than does eternal damnation for the atheist if God does exist.

Wiktionary

Origin of Pascal's Wager

After French theologian, Blaise Pascal, who formulated the wager

From Wiktionary
After Blaise Pascal

From American Heritage Dictionary of the English Language, 5th Edition