Darwin's portraying human beings as a developed species of animal and his presentation of some races as not yet having completed their development, and as species closer to animals was intensely dangerous and destructive in human history. Those who took this claim of Darwin's as their guide mercilessly oppressed other races, forced them to live under the harshest conditions, and even exterminated them.
Bryan Appleyard, author of the book Brave New Worlds, explains the tyrannical mentality underlying racism, and the results of it, in this way:
The point is that once people decide you are a lesser creature for whatever reason, either superstitious or scientific, there appears to be no limit to what cruelty they may inflict on you. And they are likely to inflict that cruelty feeling fully justified, because it is but a small step from believing another human being is inferior to believing that he is bad, dangerous, or threatening to 'superior' beings. Indeed, some may generalize the point even further and insist that all 'inferior' beings are dangerous because they threaten the life or health of the entire human race. They may then advocate sterilization, restrictions on marriage, or even murder to prevent the outcast's assault on the integrity of the species. (Bryan Appleyard, Brave New Worlds, Harper Collins Publishers, London 1999, pp. 49-50)
All human beings, however, are created the same. Human beings carry the soul God breathed into them. Every human being, with no racial difference, thinks, feels, loves, suffers, feels excitement, and knows love, affection, and compassion. And every human being also knows tyranny, contempt, and difficulty. For this reason, all though history, those who believe people of other races to be semi-developed animals and mistreat them, those who offend, oppress, exploit even one person, and those who support these practices with the false evidence and theories they produced, have committed a great sin in their ignorance.
In our time there exist cultures of relatively undeveloped human societies. These people have all human characteristics, but they lack those criteria which, from technical and cultural aspects, generally rule the world. But in each one there exist all the features, customs, and habits common to humanity. Those with hidden agendas, and those who have seen advantage in racism, enthusiastically embraced Darwin's theory and accepted these people, who were no different from other humans, as members of an inferior race and even animals. As a result of this view, even in our day people have emerged who oppress and despise backward people and communities on the grounds they have not evolved sufficiently.
God, however, completely forbids racism. In God's sight the only superiority is a person's character, his avoiding all types of sin and rebellion, degeneracy and deviation, and the superior morality deriving from his piety. Apart from his piety no human can have any superiority to any other deriving from any of his features. God reveals this in a verse:
Mankind! We created you from a male and female, and made you into peoples and tribes so that you might come to know each other. The noblest among you in God's sight is the one with the most piety (who best performs his duty to God). God is All-Knowing, All-Aware. (Surat al-Hujurat: 13)