(Original post by Hype en Ecosse)
You have to be careful with your wording of this.
Darwin was born and raised a Christian, and actually went to university to study theology because medicine didn't interest him. But during his voyages on the HMS Beagle and after the death of his daughter (Annie?) he found it harder and harder to maintain a belief in God.
After looking at life as a whole, and all the different mechanisms and the absolute cruelty that is nature he decided that it was unlikely that there was a god, as the only god he knew was the God of the bible, which is described as an all-loving necessary being.
"with respect to the theological view of the question: This is always painful to me. I am bewildered. I had no intention to write atheistically, but I own that I cannot see as plainly as others do, and as I should wish to do, evidence of design and beneficence on all sides of us. There seems to me too much misery in the world. I cannot persuade myself that a beneficent and omnipotent God would have designedly created the Ichneumonidae with the express intention of their feeding within the living bodies of caterpillars or that a cat should play with mice... On the other hand, I cannot anyhow be contented to view this wonderful universe, and especially the nature of man, and to conclude that everything is the result of brute force. I am inclined to look at everything as resulting from designed laws, with the details, whether good or bad, left to the working out of what we may call chance."
This was said in a letter to Asa Gray, a great botanist that Darwin knew. So as you can see, he never just ignored the possibility of God starting off evolution, he did heavily consider this and "[writing atheistically] is always painful to [him]"
He did come to the conclusion that it was unlikely that the God of the bible had created this, as what was written disagreed with what Darwin observed in nature. So he believed that God had no interference, but as any great scientist should, he never made an absolute statement and was open that he may be wrong.