Did you know, people are absolutely capable of a psychological behavior called "compartmentalization"? It's described to great effect in "1984", a novel by Aldous Huxley. It's when people hold obvious, and yet obliviously, two or more incongruent beliefs that normally can't both be believed at the same time. And yet, there it is, it occurs. It occurs because it's useful for the mental health of a human. So say, calling someone n---- and claiming to be totally not a racist, God-fearing Christian is something many people do. Because they can compartmentalize their behavior so that they gain the benefit of one belief, while not having to feel bad about acting on another belief many think are abhorrent. It's a winning algorithm for what many others see as very sketchy behavior.
Watch:
"I'm a Christian. I believe in the redemption offered me by Christ, and I'm forgiven of my sins. I will go and try to sin no more."
Later:
"Curse you, you lazy, good-for-nothing n-----."
"But they made me mad. I can't be held responsible for words when I'm mad. And besides, they are only words."
"Of course I'm not racist, I would never discriminate against someone like that."
"It's OK, though, my belief in Christ will redeem me no matter what I do."
There are a lot of people doing this, and probably even more looking at that and thinking it's possible, and more normal, to be angry with someone without bringing racist stereotypes to the conversation. So it's likely a racist spouting off here, and a Christian in denial about their racism.