Slavery existed in Africa and the mid east long before it was in the USA. America did not invent it, Africans and Muslims invented it.But not so Germany and Japan. And the US-American form of slavery is a very special form of "industrialized" or "capitalized" racism. The background for this racism had been the strength and endurance of the negroes. The "racism" = to see animals in human beings and to trade them like animals - had been psychologically useful for the purpose "harvesting cotton wool". The negroes had been seen as harvesting machines. The religion behind such a dehumanisation is per se an inhuman atheism.