Faith in the Face of Impending Doom?

Here's one of the big stinkers out there that bothers me and my belief in God, and it's the fact that we know, getting to the point here, that we're screwed.

1.) The Rock

Statistically, every couple of million years an asteroid falls from the sky and does terrible damage to some area of the earth, and every several million years, one rock falls that undoes everything.  The dinosaurs?  Undone.  The mammal-like reptiles before them?  Also undone.  Granted, each and every step of these undoings led to the eventual evolution of US, humans, but that's almost another argument in it's entirity.  Even THEN, we know that WE, people, were almost undone because genetic testing traces us back to only a couple of thousand people living in east Africa.  What happened here?  Is this the work of God?

2.) The Hourglass

The sun is our life source here on Earth.  Without it, not much of anything can live here.  Unfortunately, we know that in about 5 billion years time (if we survive that long), the sun's going to run out of gas.  When that happens, stars of our's size puffs up and become bigger before going nova.  Long story short, Earth will become an ember engulfed by the sun.  Besides, long before that, the sun is just going to heat up anyway, so we'll all roast if we're not off this rock by then.

3.) The Big Bummer

We know that the Big Bang happened because we essentially have the smoking gun for it -- the cosmic microwave background, which is noise... a left over faint heat signature ... from 15 billion years ago with the big bang originally happened.  The RESULT of this is that we know the universe is expanding, and we can now tell from modern tests that its not only CONTINUING to expand, but its expanding faster than it was yesterday.  The problem with this is that its going to get to a point where the universe will be so large that all the gasses will burn up, nothing will be able to recaccumulate, all the stars will die out, and the universe will grow cold.  It may happen in an infathomably long time away from now, but the point of the matter is that even if we somehow devise space travel and colonize other planets, all life in the universe is doomed eventually.

Does this suddenly seem unfair?  It seems unfair to me, because I've grown this reservoir of scientific knowledge like this that makes me question the whole POINT of life here on Earth, and I have nothing to combat it with.  WHY is it here if it's all subject to entropy and falling apart?  How can we continue to live our lives, and to live for our children and hopefully even their children, when we know that ultimately, some day, all of us will kick the bucket (and maybe sooner rather than later)?  What is the purpose of life, and us, then?

Does anyone have any input?