Here is a quote that I really like from a blog called "Magdalene's Musings":
Tonight a really bright woman at a bible study said: "I don't know why we would bother believing in God and Jesus if we didn't believe in heaven and hell." Her point was, religion makes sense in a context of earning credits and erasing debits, in a context of reward and punishment. This is straight out of the "believing in Jesus" theology. I think this is a total misreading of the gospels. I believe in Jesus, but I also believe Jesus... and this would not change if he appeared in my den right this minute to inform me that, yes, the Jews had it right, and after death there is basically, Sheol, nothingness, or, to spin it as well as possible, the bosom of Abraham. Heaven and hell are abstractions that may or may not exists. I don't actually think it matters if they do or don't. They have nothing to do with why I believe.
Christianity has to be able to hold up without the afterlife carrot. Otherwise, it's no different from anything else in our capitalist, reward/ punishment society. I happen to think it's damned different. It's about doing what's right whether or not you get a cookie at the end. Doing what is right is its own reward. Living with a Kingdom mentality requires going beyond what will benefit us, even in eternity.