Pascal, call your office!
What would you estimate to be the likelihood (that is, the prior probability) of Buddhism being true? Let this be (b).
If Buddhism is true, then you get a chance to obtain infinite jollies (metric units of happiness, j). What is that chance? Now you have to estimate the odds of Mahayana vs. Theravada. (Let's say 50-50.) If Mahayana, then all sentient beings eventually get saved, so 100 % chance of infinite jollies. If Theravada, infinitesimal chance and infinite jollies, so 1. (Let's also assume that it makes no difference to your fate which one you choose.)
If Buddhism is not true, then perhaps some other religion is true. What are the odds? Let this be (a). If so, then what are the odds that Buddhists may be saved, and thereby obtain infinite jollies? Let's say 20 %.
If no religion is true, then as an atheist, you get...let's say 1000 jollies over the course of a life spent partying. If no religion is true, but you become a devout Buddhist, you miss out on some of those jollies. Let's say you get 500 jollies.
So: [(b) x (.5) x infinity] + [(b) x (.5) x (1) - 1000 vs. [(a) x (.2) x infinity] + [(1-<a+b>) x (.8) x (negative infinity)] + 500
If Buddhism is 10 percent likely, and there is a 40 percent chance of some other religion being true, then
(.1 x .5 x infinity) + (.1 x .5 x 1) -1000 vs. (.4 x .2 x infinity) + (.5 x .8 x <negative infinity>) + 500
All clear? Edit: no, it is not. This is a mess. Now you've got *me* confused.