Here is Pascal’s famous wager, which proposes the absolute rationality of believing in God: 

If there is a God, He is infinitely incomprehensible, since, having neither parts nor limits, He has no affinity to us. We are then incapable of knowing either what He is or if He is….

“God is, or He is not.” But to which side shall we incline? Reason can decide nothing here. There is an infinite chaos which separated us. 

A game is being played at the extremity of this infinite distance where heads or tails will turn up. What will you wager? According to reason, you can do neither the one thing nor the other; according to reason, you can defend neither of the propositions.

Do not, then, reprove for error those who have made a choice; for you know nothing about it. “No, but I blame them for having made, not this choice, but a choice; for again both he who chooses heads and he who chooses tails are equally at fault, they are both in the wrong. The true course is not to wager at all.”

Yes; but you must wager. It is not optional. You are embarked. Which will you choose then? Let us see. Since you must choose, let us see which interests you least. You have two things to lose, the true and the good; and two things to stake, your reason and your will, your knowledge and your happiness; and your nature has two things to shun, error and misery. Your reason is no more shocked in choosing one rather than the other, since you must of necessity choose. This is one point settled. But your happiness? Let us weigh the gain and the loss in wagering that God is. Let us estimate these two chances. If you gain, you gain all; if you lose, you lose nothing. Wager, then, without hesitation that He is. 

“That is very fine. Yes, I must wager; but I may perhaps wager too much.” Let us see. Since there is an equal risk of gain and of loss, if you had only to gain two lives, instead of one, you might still wager. But if there were three lives to gain, you would have to play (since you are under the necessity of playing), and you would be imprudent, when you are forced to play, not to chance your life to gain three at a game where there is an equal risk of loss and gain. But there is an eternity of life and happiness. And this being so, if there were an infinity of chances, of which one only would be for you, you would still be right in wagering one to win two, and you would act stupidly, being obliged to play, by refusing to stake one life against three at a game in which out of an infinity of chances there is one for you, if there were an infinity of an infinitely happy life to gain. But there is here an infinity of an infinitely happy life to gain, a chance of gain against a finite number of chances of loss, and what you stake is finite.

Blaise Pascal, Thoughts

Pascal appeals to our reason, by asking us to recognise that reason itself has come to its limits. Instead we must make that great existential choice – we must commit ourselves. But to choose not to believe is to risk everything – an infinity of happinesses.

There is a power to this argument, but it is also fraught with problems. In particular, as Simone Weil recognised, its very logic is inconsistent with true faith.

Here is an alternative wager, put forward by Weil:

If we put obedience to God above everything else, unreservedly, with the following thought: ‘Suppose God is real, then our gain is total – even though we fall into nothingness at the point of death; suppose the word ‘God’ stands only for illusions, then we have still lost nothing because on this assumption there is absolutely nothing good, and consequently nothing to lose; we have even gained, through being in accord with truth, because we have left aside the illusory goods which exists but are not good, for the sake of something which (on this assumption) does not exist but which, if it did exist, would be the only good… 

If one follows this rule of life, then no revelation at the the moment of death can cause any regrets; because if chance or the devil governs all worlds we would still have no regrets for having lived this way. 

This is greatly preferable to Pascal’s wager.

Simone Weil, Gateway to God, p. 44 

The attraction of Weil’s wager is that she refuses to separate truth and goodness. If God exists then we have truth – even without Paradise or any eternal happiness – even if we crumble away into nothing. We had faith in truth, even if that truth turns out to be inconsistent with our eternal happiness.

And, if God does not exist, we also lose nothing, because we have not deluded ourselves with meaningless goods. She will not allow Pascal’s easy separation of a good that may be false.

Weil’s is the harder road, but it is the better road. Faith in God cannot be a gamble on a free ride to Heaven. And belief cannot mean just the mouthing of words or the holding of ideas. Belief is our commitment – belief is an action of the will – the very essence of our being.