It is clear from various things that Pascal says (e.g., in fragment 234) that in the Wager argument he partly considers himself to be making an extension of an Augustinian point. Here's a passage from Augustine's De Utilitate Credendi that can be related to the Wager argument. De Utilitate Credendi is an argument against the Manichaeans, who attacked the Catholic faith for its emphasis on belief rather than certainty. It's a different argument than Pascal gives, but it clearly has some affinities, particularly in that it appears addressed to the same kind of person (the one who refuses to allow that believing without knowing is a genuine option), and in that it proceeds dialectically.
23. But you will say, consider now whether we ought to believe in religion. For, although we grant that it is one thing to believe, another to be credulous, it does not follow that it is no fault to believe in matters of religion. For what if it be a fault both to believe and to be credulous, as (it is) both to be drunk and to be a drunkard? Now he who thinks this certain, it seems to me can have no friend; for, if it is base to believe any thing, either he acts basely who believes a friend, or in nothing believing a friend I see not how he can call either him or himself a friend. Here perhaps you may say, I grant that we must believe something at some time; now make plain, how in the case of religion it be not base to believe before one knows. I will do so, if I can. Wherefore I ask of you, which you esteem the graver fault, to deliver religion to one unworthy, or to believe what is said by them who deliver it....Wherefore now suppose him present, who is about to deliver to you a religion, in what way shall you assure him, that you approach with a true mind, and that, so far as this matter is concerned, there is in you no fraud or feigning? You will say, your own good conscience that you are no way reigning, asserting this with words as strong as you can, but yet with words. For you cannot lay open man to man the hiding places of your soul, so that you may be thoroughly known. But if he shall say, Lo, I believe you, but is it not more fair that you also believe me, when, if I hold any truth, you are about to receive, I about to give, a benefit? what will you answer, save that you must believe?
24. But you say, Were it not better that you should give me a reason, that, wherever, that shall lead me, I may follow without any; rashness? Perhaps it were: but, it being so great a matter, that you are by reason to come to the knowledge of God, do you think that all are qualified to understand the reasons, by which the human soul is led to know God, or many, or few? Few I think, you say. Do you believe that you are in the number of these? It is not for me, you say, to answer this. Therefore you think it is for him to believe you in this also: and this indeed he does: only do you remember, that he hath already twice believed you saying things uncertain; that you are unwilling to believe him even once admonishing you in a religious spirit.
In some ways I find this a more interesting argument than Pascal's, although I think it more limited in nature (in part because it has in mind as its interlocutor a member of the Manichaean mystery religion -- which is the reason why Augustine frames the argument in terms of induction into a higher religious state -- rather than Pascal's man of the world). But in Augustine, as in Pascal, it is part of a larger argument, and Augustine goes on to point out the fact that we consider it unreasonable to believe only what is certain.
Pascal is also influenced by Montaigne, who argued that there is no a priori reason not to believe in the resurrection; the reason some people are inclined to disbelieve claims that someone has risen from the dead is simply habit, so people who think that in disbelieving the resurrection they are doing more than just holding a (less than certain) belief are deluding themselves. (Pascal makes a similar argument in one of the fragments.) The connection is that Augustine and Montaigne both, in different ways, argue that it is unreasonable to try to eliminate belief in favor of something more certain in some areas of life (because those areas do not admit of certainty). Pascal sees himself to be going beyond both Augustine and Montaigne on this point by laying out more clearly why it is unreasonable to reject belief out of hand.
