When we come across a beautiful piece of art, we naturally assume that there is an artist out there, somewhere, that spent a great deal of time and energy to create the masterpiece. The natural assumption is that someone of great talent created it; not that, by some random accident, it came into being. The same is true of a good book; none of us has ever asked to meet the author and expected to be introduced to a room full of monkeys plugging away at typewriters.
Why, then, do some completely ignore the evidence of God in the world? Naturally, we should come to the conclusion that there is intelligent design and a greater being out there. Assuming there is no God is denying the evidence; this is not to confuse evidence with proof, as it does take faith to believe in God.
The simple fact that the universe exists points to a creator. Everything that exists was created by something; and the more complex the creation, the more intelligent and skilled the creator. To believe that it came about by cosmic accident is to make an assumption and try to fit the evidence to meet that belief.
Creation is not the only evidence available to us from God. There is the personal relationship that is available to anyone that wants it. Understandably, those who do not believe that God exists will completely discount any relationship with God as simple feelings that help comfort those who don’t really know any better. This is along the lines of denying that I have a wife simply because you have never met her. If you do not know me personally, you can only take my word for it that my wife exists and is not simply a figment of my imagination that I made up to comfort me.
The only way to experience the evidence that my wife is a real person is to get to know her. Simply seeing her out on the town with me would not be proof that she is my wife, but the more you get to know her and see us interact, the more evidence you would have that she is my wife. Simply telling you I have a wife is not proof that I have a wife; it isn’t even a strong piece of evidence. In order to obtain evidence the I have I wife, you need to get to know, which you can’t do until after you have meet her, and in order to meet her you would have to believe that she really existed. How would you know she really exists? You would have to see her with your own eyes.
The same is true with God. He has given us all a General Revelation through creation; that is, all the evidence that you need to “see” God is in His creation. Simply believing that God exists is not His end goal; it is the first step in building a relationship with you.