Simplicity itself. Darwin was an atheist and he came up with a hypothesis that appealed to those scientists who wanted a secular explanation (because they were atheists). So, it's all self-serving.
It is bad science, however. Incremental mutation has no means of becoming more dominant than natural variation, so there would be no way for "selection" to occur in the face of natural variations in strength, weight, size, etc. Also, radiation-induced mutation is basically radiation damage. Plenty of work on lower forms of life, and no known beneficial mutations. (The case of the moths that adapt to soot or lack of soot is only a case of natural variation, not mutation.)
Simplicity itself. Darwin was an atheist and he came up with a hypothesis that appealed to those scientists who wanted a secular explanation (because they were atheists). So, it's all self-serving.
It is bad science, however. Incremental mutation has no means of becoming more dominant than natural variation, so there would be no way for "selection" to occur in the face of natural variations in strength, weight, size, etc. Also, radiation-induced mutation is basically radiation damage. Plenty of work on lower forms of life, and no known beneficial mutations. (The case of the moths that adapt to soot or lack of soot is only a case of natural variation, not mutation.)
He was a Christian. He agonized for years about his discoveries as they pointed towards the non existence of God.
Source:
Sir Gavin de Beer, Charles Darwin: Evolution by Natural Selection.
The Life and Letters of Charles Darwin, ed Francis Darwin.
As I read it, his daughter's untimely death gave him a grudge against God.