To be fair to them, I think suspicion of people that are not part of our tribe is a normal feature of evolution.
The way we overcome that is to find ways to make each other feel like we are part of the same tribe. In sports, we wear the same colour of clothing and immediately feel a kinship with our team-mates regardless of the colour of their skin, and hostility to our opponents, whatever the colour of theirs.
We humans are, it seems, cosmetically very simple when it comes to colour.