THE PUBLICATION of his [Charles Darwin's] early Notebooks removed any doubt about some markedly non-scientific motivation at work in him when he jotted down his first ideas on evolution, within a year or two after he stepped ashore from the 'Beagle.' In those Notebooks there is no trace of the one who a few years earlier lectured, with references to the Bible, the officers of the 'Beagle' on the evil of swearing and cursing. Rather, the Notebooks contain more than one gibe, revealing in their crudeness, at a theistic outlook on existence in general and on human nature in particular.
Darwin felt antagonistic to the doctrine of creation in a far deeper sense than the special creation of every species. His real target was the primeval creation. No wonder that he felt ashamed for having "truckled to public opinion" by speaking, in the conclusion of the "Origin," of the evolutionary process as ultimately due to the Creator. In stating, around the centenary celebration of that book, that "Darwinism removed the whole idea of God as the creator of organisms from the sphere of rational discussion," Julian Huxley tried to strike at primeval creation by aiming first at the special creation of each and every species.
Darwin's remark in those Notebooks that "if all men were dead, then monkeys may make men," reveals his thorough conviction that man's origin and therefore his end too were exclusively animal. The same conviction was coupled with a contempt for anything spiritual in the following remark: "Origin of Man now proved—Metaphysics must flourish—He who understands baboon would do more towards metaphysics than Locke. . . . Our [simian] descent then is the origin of our evil passions!—The Devil under the form of Baboon is our grandfather." This remark was no less no less pitiful as far as reasoning went than the question: "Why is thought, being a secretion of brain, more wonderful than gravity, a property of matter?" This and similar utterances of Darwin, among them his call for an "evolutionary" conquest of that citadel of theism which is the mind, point at some primitive instincts at work for some patently non-scientific purposes.
Clearly, if Darwin had been just a scientist, how could he feel an overriding urge to conquer that citadel for a purpose which had to do more with crude materialism than with science?
~Stanley L. Jaki: The Purpose of it All, Chap. 2—Purposeless Evolution.