Racist is not a word that is found in the Bible. It is not there for a good reason. The shibboleth “racist” first appeared in English in the early 1930’s in a translation of a work by a Jewish Marxist, Magnus Hirschfeld. Its first known use, however, occurred in Leon Trotsky’s “History of the Russian Revolution” in 1930. He invented the word to attack the Slavophiles, i.e. Slavs that just wanted to preserve their own folkways against encroachments of Internationalism. This attitude was considered “backward” and counter-revolutionary. These “racists” were preventing the triumph of Communism. Therefore “racism” is a bad thing if you are a Communist or otherwise promote Egalitarian, Utopian/Babel-onian schemes of One World Order which must destroy distinctions of kith and kin.
Since Communism is a God-cursed, vile, anti-Christ dogma, these “racists” that Trotsky hated (and later killed) are actually the good guys. Ethnocentrism and love of kith and kin is a positive good in that it directly opposes the spread of Communism. Kith and kin is just another way of expressing what Paul says to Timothy in I Tim 5:8 “But if any provide not for his own, and specially for those of his own house, he hath denied the faith, and is worse than an infidel.” Here “kith” corresponds to “his own” signifying a larger group of related people and kin corresponds to “his own house” signifying the family members and slaves.
So, while “racism” may be social gaffe or a Communist “sin” it is not a Biblical category therefore it is not a sin by any Christian definition of the term. The Bible defines sin and racist ain’t in there.
Now, if you want to speak Biblically then one might talk about pride being a sin or hatred or some other actual categorical sin. But, mixing categories and importing the World’s neuroses into the Church can only lead to confusion and worse sin.