Statues depicting the kings of Judah (decapitated during the French Revolution).
Almost all contemporary Christians actively oppose the idea of social stratification based on race/ethnicity. Slavery and Jim Crow are regarded as stains on human history in which Christians embarrassed themselves by supporting an ungodly social order.

Why is racial stratification now regarded as sinful?

Many answers are given to this question. Most of them have to do with accusations of racism. But racism itself is a difficult term to define, and it's not among the sins discussed in the Bible. Today, racism typically describes actions and views connected to slavery and Jim Crow. As a result, Christian claims about Jim Crow and slavery being sinful because of racism amount to a circular argument: slavery was sinful because it was racist, and racism is sinful because of slavery.

Racism is also equated to hatred based on racial/ethnic heritage, but one can own slaves and believe in the separation of the races without hating one's slaves and wishing ill on other ethnicities. The Apostle Paul must have believed it was possible not to hate one's slaves when he sent Philemon's slave Onesimus back to him with an admonition for mutual love.

So is racial stratification a sin? Would God condemn the concentration of political and social power in a particular race?

The subjects of monarchy and aristocracy are useful in evaluating this question. The office of monarch is a hereditary position that doesn't relate to merit. One doesn't earn the monarchy; rather, one inherits it through blood ties to the previous monarch. One family becomes the royal family, and the political order is ruled through a specific bloodline.

The connection between race and monarchy is obvious. If monarchy is an ethical political structure than so is racial stratification. If the rulers of a nation can inherit political privilege through genetic inheritance then there's no reason to believe members of one racial group can't also inherit political privilege though genetic inheritance.

This parallel becomes more apparent when one considers a hereditary aristocracy such as existed in medieval Europe. The monarchs and nobility of feudal Christendom formed a caste in which social and political position was dependent on bloodlines rather than meritocratic virtue.

Would God support such a system of inherited privilege?

He has and he does. God promised the throne of Judah to the bloodline of David. Why? Because David was a loyal servant of God, but his descendants often were not. The history of Judah is filled with wicked unworthy kings who received the right to rule not because of their character or talents but because God preserved their line due to a promise he made to their ancestor.

Both of Jesus's parents gained the privilege of raising the messiah because they were descendants of King David. Jesus himself is a hereditary monarch with a divine right to rule because of a physical blood lineage to the ancient King after God's own heart.

Now, it's also true that Jesus deserves the throne because of his superior character and sacrifice, but this doesn't negate the fact that the messiah could only have come through the Davidic genetic line. This is highlighted by the effort the gospel writers placed into tracing Jesus' family tree back to David and Abraham. These writers knew the Jews could only accept a messiah who'd inherited the privilege to rule.

If inherited privilege is just, how could one claim racial socio-political stratification is sinful?

One of the ways this might be argued is by claiming there's some special moral exclusion of inherited privilege based on race. However, nowhere in the Bible is such a specific exclusion found. At least in the Old Testament, God endorsed ethnic stratification by specifically allowing the Israelites to keep non-Israelite slaves as permanent inherited property.

In the Nation of Israel, even the office of King was connected to race. This was made clear in Deuteronomy 17:15: "Be sure to appoint over you a king the Lord your God chooses. He must be from among your fellow Israelites. Do not place a foreigner over you, one who is not an Israelite."

Many modernist Christians (especially of the Cultural Marxist variety) would dismiss this entire dispute about inherited privilege by claiming that monarchy and aristocracy is contradictory to Christian values. These same people would probably assert that all politics should be organized on the principals of egalitarian democracy.

If these people are right, however, all of Christian history must be repudiated stretching back thousands of years, and an explanation needs to be presented for why this moral truth wasn't understood by generations of Christian thinkers.

These modernists would must also explain why God established Christ as a hereditary monarch descended from a line of God ordained hereditary monarchs, and why the early Church was ruled by elderly men who were never swayed by "the majority" or consensus votes cast by their fellow believers. Why were practical matters such as those discussed at the Council of Jerusalem in Acts 15 decided by an elite few rather than the masses? Why did Jesus choose only 12 men to aristocratically judiciate over the affairs of his kingdom?

The belief that Jim Crow segregation, slavery, and race based social stratification is a sin doesn't arise from the Bible but from the Enlightenment liberal view of democracy as an inherent good and the obsession with social equality as a central moral truth.