It's miracules that we even have existence at all and if we did not reproduce "we would not exist" to even question why do we exist at all?
And we would not question unless we had a brain to think on these things so why do we have a brain at all to question?
It's miracules to think that this all came about by chance all this complexity in us and around us that we call life.
So why does this all exist because we know it all does.
This is why so many people do believe in God.
There are more questions then answers unless...

Interesting Video

Scientific Proof of God

http://www.youtube.com/watch?feature=player_detailpage&v=LzetqYev_AI

Unless one believes the Hebrew and Greek Scriptures is the answer to it all and God did it.
Why could there not be a God?
There is no reason a God could not exist and many reasons to point out that one could or does exist.
Many people from all walks of life believe that God does exist.
Many intelligent people do.
If time is running out for us we may all see God soon.
Now that is not an impossibility.