It is reasonable to believe that there is a God who created the universe because there is no way to prove there is no god and because there is no scientific way to explain why the universe exists. If there is no scientific way to explain why the universe exists, it becomes reasonable to postulate that a supreme being created it. However, it is also reasonable not to believe in God because there is no proof that a god exists.
There is, of course, a scientific explanation for how the universe has come to be the way it is. This is the Big Bang Theory. This theory holds that the universe began as an infinitely dense fireball that exploded, leading eventually to the universe that we now have. Even if this is what happened, it does not preclude belief in God. There is no way that science can say why or how the infinitely dense fireball came to exist. This is where religion comes in.
The reason for the existence of the universe is a mystery. Since it is a mystery, it is reasonable for people to try to explain it. The existence of God is one way to explain the presence of the universe. Therefore, it is reasonable to believe that God exists.
I would say that if we take a close look around us, we can see evidence. Romans 1:20 says this, "For his invisible [qualities] are clearly seen from the world’s creation onward, because they are perceived by the things made, even his eternal power and Godship, so that they are inexcusable;..." NWT We study the universe in order to explain it, and we find that there are laws that govern the whole universe- who set these in motion? Mathematically, the odds that the earth's perfect location for life to exist came about by accident are slim.
I'm no scientist, but i know that we live in the habitable zone of both our solar system and galaxy. Not only this, our moon is the right size and distace from us to allow us to have tides and proper rotation, the tides that keep our life-giving water from becoming stagnant and useless, the rotation keeps us from roasting on one side of the Earth, and freezing on the other side. It would be a miracle for such to occur, and not only that, but for the diversity of life that we see today, to exist, if it weren't for a creator.
The Earths natural cycles are breathtaking too. There are so many, whether it is the water, nitrogen, carbon, or any other cycle, these replenish the Earths resources that sustain us.
Humans have wonderful capabilities as well, but most importantly, we have emotional and spiritual needs. We feel love, we feel happiness...and although other animals show something similair, they in no way are able to search for meaning in life the way we are.
These are just a few things, but they build in me a belief in God. I think there is solid evidence that points to a creator, and not just a cod and distant God, but one that isn't far off from us...