Us vs. Them
Racism is immoral. It's the antithesis of the teaching of Scripture. It's socially unacceptable. And it's just incorrect. There is simply no basis in fact for believing one race is inferior to another.
Even those of us who abhor racism still tend to find ways of dividing ourselves up into "us" and "them." It gives us a way to feel superior to "them," whoever they are.
"They" could be liberals, conservatives, foreigners, refugees, addicts. "They" aren't worthy of our respect. It's OK to refer to "them" with dismissive and disrespectful labels, like right-wing, left-wing, radical, extremist, nuts, libtards, teabaggers, and so forth. It's OK to feel superior to "them."
Except it's really not OK, especially for a follower of Christ. No matter what society says, there is no acceptable way to demean or disrespect any group of people. Not ever. There is no one I can justly consider to be inferior to me. Galatians 3:28 says "There is neither Jew nor Gentile, neither slave nor free, nor is there male and female, for you are all one in Christ Jesus." That passage made it clear that the "us vs. them" rules of the day no longer applied. 1 Peter 2:17 puts it bluntly, "Show proper respect to everyone." There is no one I'm allowed to disrespect.
Of course, it's OK to disagree with people. It's OK to express opinions on divisive issues. It's OK to let people know if they're on the wrong path. If fact, love compels us to do so. As 1 Peter 3:15 says "Always be prepared to give an answer to everyone who asks you to give the reason for the hope that you have. But do this with gentleness and respect."
But none of this allows us to devalue another person or group. The only being in the universe qualified to determine a person's worth is their creator God. How highly does he value all people? He considers us all to be worth dying for. How can I call myself a follower of Christ if I fail to value what and who he values?