Pascal's Wager

Pascal's Wager is a theological argument by French philosopher Blaise Pascal that was published posthumously in the 1669 work Pensées.

The Wager claims that one ought to believe in the Judeo-Christian God described in the Bible because, if that God exists and one believes, one stands to gain everything, but if that God exists and one does not believe, one stands to lose everything. Conversely, if that God does not exist and one believes, one loses nothing, and if that God does not exist and one does not believe, one also loses nothing.

Flaws
The Wager fails on many counts.

False dichotomy
The Wager presents an incomplete scenario by offering only two options: either the Judeo-Christian God of the Bible is real, or there are no gods at all. If one grants even the possibility that the Judeo-Christian God of the Bible is real, however, one must also grant the possibilty that any other god that has been worshipped by humans may also be real.

Thus, it is not the case that one stands to lose nothing by believing in the Judeo-Christian God. If, for instance, Thor is real and the Judeo-Christian God a fabrication, then one who believes in the Judeo-Christian God stands to lose a great deal specifically because the Judeo-Christian God does not exist.

Cast differently: the Wager can be used to argue for belief in any deity. If, for instance, Zeus exists and one believes, one stands to gain everything, but if Zeus exists and one does not believe, one stands to lose everything. Therefore, it is beneficial to believe in Zeus rather than not to believe in Zeus.

Bettor's conceit
The Wager presumes that an all-knowing God cannot tell the difference between genuine belief and artifical belief. It also presumes that an all-knowing God would reward genuine belief and artificial belief equally.

This discounts the possibility that such a God would, instead, punish nonbelief and artificial belief equally.