I don't honestly think we find out this answer until it's all over.
I consider myself a Christian but I'm not particularly rank-and-file. I do think that there's something out there after this, even if that thought is just a way for our species to calm its fears about death. I'm okay with that.
And I truly think that when it's all said and done, you end up in this Place--heaven, the ether, Deep Space Nine, I don't know--and there's somebody there with all the answers. And that's when you find out why you were here.
Bear with me on this. It's a little meandering but it gets to a point.
One of my favorite Bible verses is Hebrews 13:2, "Do not forget to entertain strangers, for thereby some have entertained angels unawares." I think of this as one of my mantras in life. There's that cheesy successories-style saying about how you should be nice to everybody because you never know when you're going to be the only person who was nice to them that day, or something. A barfy way to say the same thing.
(By the way, the worst thing that ever happened to the written word, other than The Bridges of Madison County, was the switch from the prevalence of the King James Bible to the New International. The language in the KJV is absolutely melodical.)
But the reason that verse resonates with me so strongly is because I truly think that it could be that you are here for one specific moment, for one specific interaction, for one specific "accident" that isn't an accident at all. Winston Churchill says the same thing in his own Churchillian way that you are here for one important reason.