Charles Darwin had a theological motive in developing his theory – to give support to a rejection of divine causality and to deal with the problem of evil. He had this view at the beginning, when he was trying to explain the injustices he saw in nature as not part of a divine cause. This view grew more after the death of his daughter when he thought that nature was simply cruel itself – by then he ceased believing in God, but his theory reflected his philosophical views.
The most famous quote proving this is:
“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.” (Darwin’s letter to Asa Gray)
The purpose of Darwin’s theory was to explain the suffering and death that he saw in nature. The idea of natural selection proposes that there is a ruthless competition in nature and some species win and others lose – and ugliness, death and cruelty are the accidental, random, unconscious results or mutations and selection pressures. Thus, God is removed from nature entirely.
Here’s a quote where he makes that clear:
"The old argument of design in nature, as given by Paley, which formerly seemed to me so conclusive, fails, now that the law of natural selection has been discovered. We can no longer argue that, for instance, the beautiful hinge of a bivalve shell must have been made by an intelligent being, like the hinge of a door by man. … Everything in nature is the result of fixed laws." (The Autobiography of Charles Darwin)
This is the foundation of evolutionary theory. “Everything in nature is the result of fixed laws”. Thus, God is removed from direct influence, design or creativity in nature (not to mention that there can be no supernatural interventions also). At best, one could propose that God is merely the “Lawmaker” which is essentially the Deist view and virtually indistinguishable from atheism.
Again from his autobiography:
‘A being so powerful and so full of knowledge as a God who could create the universe, is to our finite minds omnipotent and omniscient, and it revolts our understanding to suppose that his benevolence is not unbounded, for what advantage can there be in the sufferings of millions of the lower animals throughout almost endless time?’ (The Autobiography of Charles Darwin)
This indicates Darwin’s theological motive.
Here are a few more quotes that give proof of the same thing:
The Descent of Man was written to show Lyell, Gray, and Wallace that a God-less account, relying on random variation, natural selection, and sexual selection, could explain every aspect of human nature that might appear too elevated, too divine-like, to have been caused by natural processes alone. Morality was just one aspect Darwin attempted to explain, but it is important that it must be understood as an attempt to remove any need for God. Darwin’s is strictly and exactly speaking, a God-less account of morality.
discovery.org/a/9591
Early in his career, Darwin saw the indifference of natural law as an answer to the era’s religious doubts about how a benevolent god could permit human misery; cruelty and pain, he argued, should not be seen as moral issues, but as inevitable outcomes of nature. After Annie’s death, however, Darwin’s views darkened, and in a private letter he railed against the
“clumsy, wasteful, blundering low and horridly cruel works of nature!”
amazon.com/Darwin-His-Daughter-Human-Evolution/dp/1573221929
As pointed out in the third chapter, Darwin came to see that the
ongoing need for all animals to compete for the means of life created a
continual pressure for selection. This factor, along with what he knew
about variation and inheritance were integral to his species evolution
theory.
Darwin thought he had identified a process that would explain the
development of all forms of life without divine intervention.
voc.ed.psu.edu/projects/publications/books/spring%202003/Gilli.pdf
This dictum (scientism),
applied to biology by Darwin, meant primarily that evolutionary theory could have no place for divine causation, because such causation was assumed by definition to be supernatural.”
These three ideals of modern science, besides ruling out divine causation, also ruled out all teleological causation.” Teleological causation, in the sense of self-determination by an organism to reach some telos or goal, would obviously threaten the ideals of predictive determinism and of reducing wholes to their parts. it would also threaten scientism, because self-determination would be an inner, invisible type of causality not observable to the senses or to any scientific instruments designed to magnify
God and religion in the postmodern world – David Ray Griffin, p 75
I took some time this morning to research those quotes. This is not at all a comprehensive list or view of the topic, but I hope it was helpful towards answering your question.
There is a book length study on this topic that you might want to consider also:
Darwin’s God by Cornelius Hunter
I haven’t read that book but it gives a comprehensive overview of the theological origins and motives of evolutionary theory.
