So asks this essay and gets the whole thing wrong.
Darwin’s theories (plural) are not controversial because they imply that species are mutable. This was a widely held view by preachers, moralists, Aristotelians, naturalists, breeders, formalists, folk biology, and even biblical translators.
Darwin was not controversial because he implied racist ideas about humans. He never did and the racism that is sometimes associated with his ideas preceded him by centuries (and were good Christian virtues) and were mediated by those who disagreed with him.
Darwin was not controversial because he thought the age of the earth was large. This preceded him also, and was settled in the late eighteenth century, although the present value wasn’t finalised until the 1960s.
Darwin was not controversial because his account of humans being animals contradicted the Bible. Linnaeus knew humans were animals a century earlier, and indeed the only issue was whether humans were animals with souls (or if all animals had souls), which Darwin never implied anything to the contrary.
Moreover, it was Christians who rejected the literal interpretation of the Bible, long before Darwin (beginning with the Alexandrian school in the second century), and those who realised that the global Flood was a myth (or an allegory) were Christian geologists a half century at least in advance of Darwin.
No, the reason why Darwin was controversial is very, very simple. Darwin argued that complex designs could arise without a mind to guide it. In short, his controversial idea was natural selection (and sexual selection, but even that preceded Darwin). Almost from the day it was published, critics attacked the implication that the living world was not all that special, and that it lacked a Plan or Meaning. Theologians, moralists and even scientists objected to this, and while even most of the Catholic Church accepted common descent and modification of species, it was natural selection they hated.
All the supposed “controversies” of Darwinism (or that phantom, “neo-Darwinism”) are post hoc attacks based on the prior objection to the lack of a guiding hand in biology. Don’t like natural selection? Attack Darwin by calling him a racist or blaming him for the Holocaust. Say he is antiessentialist. Say he is anti-religion. No matter how much evidence one puts forward that these are deliberate lies manufactured by those who hate Darwin for natural selection, it won’t stop the prevarication industry.
Sensible philosophical critics of Darwin focus on selection for that reason. It undercuts our prior belief that We Are Special. Human mentation, cognition, language, morality, religion or economics is somehow privileged in the universe. Bullshit. We are an animal and we arose without the universe seeking us (although, as I have argued, a deity might choose this universe because we evolve in it). The human exceptionalism which critics like Fodor, Fuller, Plantinga and the rest presume but do not argue for unfairly places the onus on Darwinians. It is time to stop taking them seriously.