For a long time now, atheists have attempted to paint Christianity as a "white man's religion", a racist ideology that supports slavery and propagates the idea that caucasians are the greatest of all the races. As this image above shows, the opposite is true. The Bible counteracts racism in three ways: It elevates all "lesser" races to the level of mankind, it degrades all "higher" races to the level of "Adam", and it offers salvation to all people of every tribe, nation and tongue.
Through its description of the single origin of mankind, the Bible utterly refutes the idea that race even exists. To be sure, there are different races, but not in the sense that we understand it. The angels are a race of their own. Humans are a race of our own. Each animal kind belongs to a separate race. But humans, rather than being divided by race, are Biblically divided by nation. A nation is not a subset of humans that are "better" or "worse" than one another. Rather, nations are usually divided by their borders. Even brothers can be a different nation, as is seen in Jacob and Esau; twins who fathered two entirely separate nations: Israel and Edom. Though God certainly made different covenants with these two nations, His judgement of each individual within those nations is equal.
Thus, in God's eyes, all men are equal, exactly as He created us to be. But just because He loves us all equally does not mean we are free from judgement. Another thing we have in common with our father is sin. Just as Adam and Eve rebelled against God, so do we. That means that yes, God will judge people of a "minority" race. But He'll equally judge the "majority". He'll judge the black person in America just as He'll judge the white person in America. He'll judge the white guy in Africa as easily as He'll judge the blacks. Black, white, old, young, poor, rich, upper class, ruling class, God shows no partiality in His judgements. Ironically, this will upset a few people who claim (correctly) that racism is evil, because they want God to show partiality to those races whom they believe are oppressed. This attitude is extremely racist.
But by far the greatest way in which the Bible flattens racism is that God's salvation is open to all people of every tribe, nation and tongue. No one needs to jump through an extra hoop, pay an extra price, make an extra sacrifice etc. Any descendant of Adam can have their sins forgiven just as easily as any other. 100% of humanity, as long as they remain alive, is eligible to receive God's gift of grace.
Thus, all claims that Christianity is racist, or even that the Bible could legitimately be interpreted that way, are false. You simply cannot fit racism into a book that denies race even exists. Even the few statements which can be misquoted to fit a racist's agenda cannot be made to be racist in light of the rest of the Bible. It simply cannot be done.