What you are really explaining is the tribalism impulse that is imbedded within the base human ego. The ego is also the base human defense mechanism. Thus there is a highly explosive element within the tribal impulse.
Like everything in life tribalism cuts both ways. Its positive purpose is to foster community action for the good of those of similar characteristics such as race, religion and nationality.
Its negative offset (everything in life has a negative offset because of the universal law of probability balance) is to promote fear and hatred between those of unlike characteristics — “the other.” The clash between differing political ideologies is simply one more element of the negative tribal offset.
What is occurring more than even in the world today is what I call spillover. Meaning that as the earth is a limited entity and there are more are more people, it is forcing the mixing of all sorts of peoples of differing tribal impulses. So like an overcrowded cage of rats, the friction rate among humans of all kinds is NOW going through the roof.