The concept of one true God comes down through history from Adam till world religions today, not only the Abrahamic religion. The ancients of Noah’s time had a concept of a most high God who was over all gods and was at the very top where there was room for one only. The word AN or DINGIR used an asterisk symbol and had associations with the sky - hence the star symbol - and what is at the top of the metaphorical tree - its apex - the zenith. The Christ person is like one of two - Son together with Father - while the Father Himself is the one of one. You can say today “the one true ...” or “the one and only ...” in situations where there can be only one who qualifies for a topmost title or position. This is that ancient concept all through history applied to beings. Most heirarchical systems have one or two at the top and just one at the very top. Heaven is like this. Paul described it as One God and One Lord. Ultimately God is greater than Lord.
