It seems to me when you look at ancient religions, they mostly function as ways of hardening tribalism. Ancient religions did not really ever say “your gods are not real.” They said, “your gods are inferior.” This fact is sometimes used to prove the greater perniciousness of Christianity, since it drove Christianity to proselytize others, and this is a great evil, to the modern mind. The ancient pagans did not often try to proselytize the followers of other gods. But the forcible conversion of unbelievers is no part of Biblical Christianity and happened more rarely than most people seem to think. On the other hand, when you say, “your gods are inferior,” given the way religion worked in ancient times as an inseparable aspect of a particular ethnic group’s culture, what you were actually saying was, “you are inferior.” The inferiority of another people was justification for attacking and enslaving them. And how did you know they are inferior? Because you were able to attack and enslave them. If their gods were stronger than your gods, they would have protected their people from you. So yes, they didn’t proselytize followers of other gods, but they did attack and enslave them all the time.
The statement that their gods were not just inferior, but in fact fake, creates a whole different dynamic. In that case, they are deluded, being tricked, ignorant, blinded. Now, you say, wouldn’t this create the same superiority mindset, since we are the people who are not blinded, being deluded, etc? Well, perhaps, but that it depends on the explanation for why it is that some people see the truth while others do not. If your explanation is that white people are just better, then yeah, you’ve still got a problem. But if your explanation is that the world is all in darkness due to a curse by God for their rebellion, but God in His grace and forgiveness is freeing the world from that darkness, and we people who see the light are just the means that He is using to bring that truth to the world, then there is no basis for any claim to superiority. Of course, this is precisely what the Old and New Testament teach.
The Old Testament had something new, unique. In Genesis 12, God gives Abraham a promise that in him all the families of the earth would be blessed. That promise in Genesis 12 starts out feeling like normal tribal stuff- I will be your God and the God of your people, your nation will be especially blessed, etc. But that last part- that this blessing wasn’t just for Abraham, wasn’t just about Abraham, but was for the whole world through Abraham, makes it fundamentally different. And constant statements in the Old Testament showing that God is not just the God of Israel, but that He is sovereign over Babylon, over Egypt, over Greece, over Nineveh and all the rest, reinforce that truth.
Because of the universal nature of Israel’s God and of the promise Jehovah made to Abraham in Genesis 12 that is the whole reason why Israel exists, the attitude toward other nations ultimately will change. The natural tribalism will give way to a desire that other nations see the truth, that only Jehovah is real and their gods are delusions and demonic lies. This is something the Old Testament mostly anticipates happening when the Messiah comes, and this is precisely what He sets in motion when He tells His apostles in Matthew 28:18-20 to go out into all the nations and make disciples to Jesus Christ. It is the end of tribalism, one of the main weapons that Satan uses to inflict misery on the world. The Biblical religion teaches that man is one family, equal before God, intended to dwell in peace and harmony with one another, without one ruling over another.
As we said before, there is still, within true Christianity, in-groups and out-groups. But the basis for one being in the out-group has changed- not natural inferiority, but faith in Christ. Anyone in the out-group can be part of the in-group any time they want, and it is the fervent desire of every Christian that unbelievers become believers. This, too, turns the old tribalism on its head. Christianity does not set up barriers to keep the outsider out (note, this is not a comment on immigration policy, which should thoughtfully reflect the duty of civil governments toward their people) but does everything it can to bring the outsider in.
And we also acknowledge that this is a slow and gradual process. A great deal of racism, hatred, and oppression has been perpetrated in the name of Christianity. This in no way falsifies the point, since the Bible expresses this as an aspect of corrupt human nature, that which needs to be overcome. The difference is, this teaching of love for the enemy, of concern for those outside of our own tribal groups, of a desire that the human race should be united, of a belief that people are fundamentally equal before God, is not present in the ancient religions at all, but only in Christianity, even if imperfectly expressed and lived by Christians.
It also does not falsify the point to bring up other religions with similar universal aims such as Islam or Mormonism, since those religions derive from distorted understandings of Christianity itself.
But despite the best efforts of many today, the universal focus of Christianity cannot be maintained without Christianity itself. Modern philosophy and political movements such as Marxism have tried to maintain that the universal equality of mankind and the end of national divisions can be achieved through human effort, but God quashed all these efforts forever at the Tower of Babel, and they remain quashed. The doctrine of justification by faith alone is absolutely necessary to true universality, because it puts all men before God on the same footing- that we are in His favor by grace alone. Without that, and without the transformative power of the Holy Spirit showing us that truth, the old pride, the old hatred, the old fears will rule, and mankind will remain in its tribalistic misery.