"Social Darwinism" existed long before Darwin. It's just a peculiarly ugly form of racism. Christians were notorious for that long before the mid 19th century.Surely you have heard how mechanistic evolution underpins social Darwinism, which is guilty of many ills, including the ones I mentioned.
Social Darwinism is simply racism in a scientific disguise. And even though modern science has clearly demonstrated that the differences between the races is extremely superficial genetically, it's almost entirely cultural and environmental, there are still Social Darwinists. Around here where I live, they are almost exclusively Christians. From the KKK to the Christian Identity Movement to a guy down the block from my house, all the serious racists I know are very very Christian.
And that's how it's always been in this ever-so-Christian nation I live in. Racism from Hell, and it's usually supported by Scripture, although they'll dress it up as Science when that justifies their evil ways.
Tom