Europe, after the rise of the heretics, is a good example of culture having a stronger influence than race. Most of southern Europe was united under Justinian I, but heresies caused a cultural divide.
Although the French and English were white, they often killed each other over religious differences. If Europe had maintained a single religion and followed the Roman Empire’s zero tolerance of vocal minorities, the culture wars would have been minimal.
At least Karl Marx would have been executed for heresy before he could spread his influence and cause the communist problems we have today.