
If the followers of God continue living a life which ultimately makes them happy in this world, then even if it turns out that the God concept is simply a myth, they haven’t lost anything. If the purpose of life was simply to 'have a good time', then they achieved it. However, if God did turn out to be a reality then they did really well! The possibilities for the theist: “No loss” or “Eternal Gain”.
On the other hand, the nonbeliever, according to Pascal, is in a slightly more precarious position. If life was simply a one time show, then there is no extra gain. The theist was happy in his life, and so was the atheist. However, if God was a reality then his existence would surely take a turn for the worse. The possibilities for the atheist: “No gain” or “Eternal Loss”.
Pascal posits that a person should "wager" as though God exists, because so living has everything to gain, and nothing to lose. Not everyone will agree, but it is an interesting position...