Pascal's Wager seems intriguing and convincing, doesn't it? And it comes from somebody who really knows what he is talking about, being a master of probability theory himself. It's a very simple but essential and relevant supposition.
Let's assume there is a God and an afterlife. Then if we are right, we won't be disappointed. We will have backed the "right horse," so-to-speak, and are in heavenly bliss, eating fruits from the trees and being surrounded by voluptuous goddesses.
What if we are wrong though? What would happen if we erred and there is no God or paradise, and it was all just fabricated lies and fiction? Well, so what? We will be dead and won't feel a thing. So who cares if there's nothing after death. Nothing will happen to us. We will be sleeping safe, sound and dreamless in our tombs.
Yet if we assume there is no God, and it turns out that there actually is; that would be the worst case scenario. We would have to burn in hell for eternity! It's not just a few hours, days or years! This is serious business: It's going to be for all time! So you see Pascal has a point there.
However, there are a few problems with this theory. First of all, if people believe in God only for the sake of convenience and to try to save their own hinds (which probably a lot of people do anyhow), then God would see through it and the faith of these people would lack both substance and weight.
A second point could be the fact that Christians just got it wrong, and maybe we will be coming face to face with Allah or Krishna instead. There is no absolute guarantee that the Christian religion is indeed the true one, no matter what the Bible or local priest may say on this matter.
The third, and perhaps most important, point is the fact that we would choose to lead a life of ignorance, not one based on our own active discoveries and truths. We would not make our own inquiries, while taking half-examined given truths as granted. It would undermine philosophy, which is there to ask serious and hard questions about our existence, our role in life and our purpose in the universe. These things cannot be taken lightly.
But what I like most about Pascal is his emphasis on feeling and intuition over reason and logic. I believe, along with various existentialist philosophers, that we all need to have faith in something and that human life cannot be explained with science only. We are more complex than that and our capacity to feel, have compassion, create art and philosophy is what our humanity is really based on.