Who knows?
People have been asking those kinds of questions since we've been around and they've never been able to agree.
My opinion is, be thankful they're gone whatever the cause.
I think, people might disagree with me on this, if there is something greater then all he or she or it cares about is we try to do good in the world, and we're better at doing that sober. And if there turns out to be nothing, well, what's the harm in living that way? =)