Just as an individual has his ego, any social collective has its ego. They are called individual ego and collective ego respectively. The common denominator between the two is that both of them are a survival mechanism. Unconscious, that is, unawakened, individuals and social collectives typically try to secure their respective survival by labeling others as inferiors to themselves. This way they can continue to live in the illusion that they are separate beings without making any effort of their own.
Individuals who are controlled by their ego also tend to be controlled by the ego of the social collectives (they think) they belong to, which include nations and religions, among others. Then many followers of the collective ego, who behave otherwise as law-abiding citizens, may say and do terrible things, including inciting atrocities and actually committing them. I've studied, though rather superficially, three pairs of followers of probably the most dangerous type of the collective ego in modern history - chauvinism - and their victims.
Though I try to be tolerant of others and their opinions that are different from mine, I don't find it morally right to even remain in touch with those who have turned out to be supporters of such poisonous ideology so that I may not be indirectly complicit in it.
PS: Collective Ego by Leo Gura