Personally, I find it interesting that the idea of African Americans being the descendants of Ham and thus servants of whites in perpetuity came into prominence at that same time.

Also, preachers in England and the US started emphasizing the passages in the Bible (from both Paul and Peter) that slaves should obey their masters as they would Christ. The passages concerning the treatment of slaves (Exodus, or Deuteronomy) were also brought up partially to address cruel masters but also to show that slavery was condoned by God. He wouldn't have rules for it if He didn't want it to exist. He outlawed murder and theft but not slavery, so it must be ok. Those are the types of arguments put forth by the Protestant Clergy in the Calvinist churches of the south.

Darwin may have been a racist. Shoot, almost all whites were racists back then and thought whites were superior to all others. However, to use that as an argument against evolution is simply an ad-hominem fallacy and does not provide any evidence as to the truth or falseness of evolution itself. Just as the pulpit pounders preaching in favor of slavery does not provide evidence as to the truth or falseness of the Bible or Christ's sacrifice.