I am currently a storyboard artist working in TV animation at Rough Draft Studios.
Well you're certainly correct that spiritual revivals don't always bring golden eras of justice in their wake. Human beings are fallen, after all. Not that I don't hope for a revived sense of religiosity in our country, but unfortunately it'll only be the first step.
It was a little difficult for me to follow your lines of thought here, but from what I understand your main worry is that a multi-racial society will be inevitably chaotic due to human tendency toward tribalism, and that it would be better to keep us separated into our respective "peoples," correct?
While I can understand where you're coming from, I think it's taking an oversimplified view of history. People are certainly tribalistic, but I think our in-group identities are more complex and malleable than simply "people who share our physical features." After all, having practically identical racial features didn't stop the various peoples of Europe from killing each other for centuries. In my humble opinion, I would say that religion is a huge factor in tribal identity, probably moreso than race. It's been common in most of human history to have state religions (often compulsory), as it was a means to ensure societal cohesion. And there was a long period in history where people viewed the world primarily as divided between "Christendom" and non-Christian nations.
All this is to say, I believe ethnic and national identity is more malleable than you might think and need not rely on physical characteristics. And as a Christian, I would point out that Christ in his teaching has repeatedly called us to look beyond our racial divisions (as in his parable of the Good Samaritan). It would do us all good to not spend too much time fussing about race.