It is not a coincidence that the New Testament is written in Greek, Christianity was adopted by Greeks, and the Church of the first centuries has a clearly Greek identity (Cf. Greek Orthodoxy – From Apostolic Times to the Present Day). After the ancient Greeks’ unbelievable attempt to get close to Him, God was obliged to respond. Christianity is this response. The same happens in the primary, properly personal, level, i.e. with each person.
So-called “pure monotheists”, whether they belong to the Judaic, the Muslim, or any tradition of such a kind, they are in reality not monotheists but atheists. Abolish the Trinity, and you also abolish Oneness. After such an abolishment, the One that is worshipped is not the God, but the idea of a creature.