Belief in God is rational.
Everything has a cause. So unless there is a first cause, then you would have an infinite regress. And then nothing could exist. Therefore there must be a first cause. Therefore God, the first cause, exists. QED. (You could prove the first step a priori that everything has a cause by noting that nothing can come from nothing. This makes it a priori, not just an empirical observation).
race. I have thought for a long time that the way nature operates to take one species and make it into two or more is to start slowly with race. I based this idea on Darwin. The idea is that you take one species and separate it. You put one group on some island somewhere. Then you take another group and put it elsewhere. After a short amount of time that one species will be two species. That is what race is. Race is you take a group of humans they go down to Africa. Another group goes north. Eventually they become two species.
But added to this I need a little wisdom from the Talmud: that is is not a good idea to go against nature,- because nature will win.
But that still does not mean anything about how to treat other people. It has to do with groups but not individuals.