I suspect that most people have a residue of feeling that Darwinian evolution isn’t quite big enough to explain everything about life. All I can say as a biologist is that the feeling disappears progressively the more you read about and study what is known about life and evolution.
I want to add one thing more. The more you understand the significance of evolution, the more you are pushed away from the agnostic position and towards atheism. Complex, statistically improbable things are by their nature more difficult to explain than simple, statistically probable things.
The great beauty of Darwin’s theory of evolution is that it explains how complex, difficult to understand things could have arisen step by plausible step, from simple, easy to understand beginnings. We start our explanation from almost infinitely simple beginnings: pure hydrogen and a huge amount of energy. Our scientific, Darwinian explanations carry us through a series of well-understood gradual steps to all the spectacular beauty and complexity of life.
The alternative hypothesis, that it was all started by a supernatural creator, is not only superfluous, it is also highly improbable. It falls foul of the very argument that was originally put forward in its favour. This is because any God worthy of the name must have been a being of colossal intelligence, a supermind, an entity of extremely low probability — a very improbable being indeed.
Even if the postulation of such an entity explained anything (and we don’t need it to), it still wouldn’t help because it raises a bigger mystery than it solves.
Science offers us an explanation of how complexity (the difficult) arose out of simplicity (the easy). The hypothesis of God offers no worthwhile explanation for anything, for it simply postulates what we are trying to explain. It postulates the difficult to explain, and leaves it at that. We cannot prove that there is no God, but we can safely conclude the He is very, very improbable indeed.
