Christianity & Racism
The distinction between two or more groups of anything opens the possibility for a value judgement comparing them. A girl can ask her classmates what their favorite color is, and her classmates can express their opinions and defend their choices using various evidence and argument. The girl's hypothetical question, however, can be asked and answered from a subjective non-biased position only because "favorite color" is a fairly random and fluid aspect of a person's identity. Most people can change their favorite color at whim depending on their mood or convenience.
Race, however, differs from color in that no person is non-racial, and thus no person is subjective or unbiased when dealing with racial preferences. Race can't be changed. A person's racial identity can sometimes be disguised (Michael Jackson, for example), but it can never be altered. Because every human possesses an immutable racial identity placing them in a race, within a spectrum of other races, races are a necessary category that can be compared to one another. However, there is no subjective person capable of value judging them fairly. Of course, the whole process of evaluating different groups of people is complicated by ethical and philosophical factors that aren't relevant when comparing other group categories like favorite colors.
It is within these ethical complications that racism arises. Accusations of racism are not technical facts, nor are they inspired by analysis, they are religious and moral value judgements made against people and systems perceived to violate a specific moral system.
The fact that racism is a moral judgement rather than a technical fact does not, however, render it illegitimate or unreal. As Christians, we understand that spiritual reality creates and demands morality; the existence of a creator father God implies a behavioral mandate just as children implicitly understand they must obey the rules outlined by their birth fathers (at least while they live in his house, and we all live in God's house).
Technical facts are revealed through creation, while moral values are normally revealed through direct revelation. If Christians are to define racism, we must do so through a scriptural theology. Our moral judgement of racism must arise from an understanding of it presented by the Bible. Because the Bible is the only agreed upon direct revelation uniting Christianity, any other basis must be specific to a particular denomination, tradition, or theology and cannot be swiftly labeled a Christian sin but rather a "Catholic sin," "baptist sin," "Orthodox sin," etc.
So where in the Bible can Christians begin defining a concept of racism so as to condemn it on moral grounds? This is already asking the wrong question. Theology is supposed to be exigetical rather than eisegetical. We shouldn't be looking for a scriptural justification to condemn racism, we should be looking first to see if racism even exists from a biblical perspective. Even in modern Bible translations the word "racism" never appears. The fact that translators have not been able to find any scriptural text capable of being translated as "racism" suggests Christians should not participate in accusations of racism because it's not a moral concept that arises from divine revelation.
It's not that simple, however, because many Christians claim racism is a moral reality because it falls within the definition of other sins that scripture explicitly discusses. These claims primarily fall into three categories: hatred, favoritism, and injustice. 
Some claim racism is a form of hatred and therefore a sin. Few would deny the Bible condemns hatred, but it is not certain racism is hatred, or that racism is hatred in the same way the Bible condemns it. Google defines racism as:
"prejudice, discrimination, or antagonism directed against someone of a different race based on the belief that one's own race is superior."The belief that one, or one's group, is superior, however, is not an act of hatred. Neither is holding prejudice, practicing discrimination, or exhibiting antagonism. All these things are appropriate in the right situations. If I know I run faster than another person then my sense of superiority at running is simply an acknowledgment of reality. Prejudice and discrimination are both necessary aspects of human judgement. If you know that violent crime rates are especially high in a certain part of town, or that polar bears are known to eat people, exorcising prejudice and discrimination surrounding those dangerous factors is just an expression of common sense. A normal responsible father won't let his teenage daughter spend time alone with a group of ex-convicts because he possesses a sense of healthy prejudice and discrimination and wants his daughter to remain safe. The father doesn't hate the ex-convicts, he just doesn't trust his daughter with them. Antagonism doesn't require hatred either. Men have been going to war with each other for thousands of years without hating those they war with (although the overlap certainly occurs).
The Bible condemns favoritism in some situations involving Christians favoring rich people over poor people. However, it encourages favoritism in other situations, and those situations often involve blood relationships. A father who favors his own child over other people's children is not committing sin, he's acting like a quality father. In the same way, race is, by definition and DNA, an extended family, and favoring a person based on blood connection doesn't constitute the kind of favoritism the Bible condemns.
Finally, some Christians claim racism is a form of injustice, and the Bible condemns injustice. Justice, however, is giving people what they're due, and what people are due depends on a legal and social situation relative to each society. In a society organised around racial identity, justice requires treating people of different races differently. This is how enslaving someone in twenty-first century America might be unjust while enslaving someone in the first-century Roman Empire might be just. The Apostle Paul acknowledged this in his epistles by repeatedly instructing Christian slaves to obey their masters and Christian masters to give their slaves their due. However, this relativism can only be extended to the borders of God's creative mandate. If a society is constructed on the premise that keeping one wife exclusively to oneself is an act of injustice than that "injustice" must be ignored in favor of the true justice of monogamous godly marriage. In the same way, a society organized on post-racialism or "color blindness" is operating in a delusional way that doesn't correspond to God's creation of different ethnic families, and is therefore delegitimizes itself by asking us to ignore our kin groups.
In conclusion, racism is a highly dubious moral construct that finds no expression within the Bible. This should be apparent enough from Christian history. Neither racism nor anything like it was regarded as sin until the very recent modern era. It wasn't until the infiltration of 1960's ideology into churches, colleges, and seminaries that most Christians began conceiving of a racism sin, and a mere sixty years of precedent is not convincing when compared to the two thousand year history of the church.
 Galatians 3:28 is as relevant to the topic of racism as it is to sexism and transphobia (in other words, it's not relevant at all).