Frankly, the two choices offered by Standard Christianity (either heaven or hell) don't appeal to me. Neither option has any definite evidence that they exist. I go with what I know: I have no memories, good or bad, of before I was born and my consciousness switched on. I suspect it will be the same after I've died. Just nothingness. I get a certain amount of comfort from this concept.
I think the standard line is that souls are created when you are conceived, and then they are semi-infinite. Or rather, once you join God in heaven, you are "outside time and space" like God and the angels are, and so the time evolution of the Universe doesn't affect you anymore. It always seemed like a much worse punishment to exist for eternity than to cease to exist (talk about ultimate boredom), but sometimes I hear it phrased this way, that you don't experience time the same way after you die. Maybe it's like in
Slaughterhouse Five, where you experience all time at once.
You can't PROVE that there's no afterlife-- no one can. If you can take it on faith that the Christian God created the Universe and knows what's going on, He tells us that the only way to eternal life is to believe in Jesus.
However, if you don't find the theological arguments convincing, there are also the cultural aspects of Christianity. Even though the historical Jesus was most likely an apocalyptic Jew calling for a revolution against the Romans and the Pharisees, the perspective of Jesus as an anti-capitalist ("sell all of your possessions and follow me"), peace-loving ("turn the other cheek") hippie is kind of appealing to me. I find little to argue with in the Sermon on the Mount.
You could start with this, join a liberal Christian church, and "fake it till you make it." Maybe you have to go this far before Jesus comes to live in your heart and then you
know that being a Christian is the right way to live.