The oneness of God (“the Lord your God is one) has indeed been around since the beginning but the apostles did not teach the idea that the Son and Spirit are manifestations. Any school child with a modicum of intelligence can discern the NT treats the Father, Son, and Holy Spirit as three entities not as manifestations of God.
Hisway quoted from John whose gospel not only tells us that the Word and God are one but they existed together before the beginning – separately. The NT writers go to great pains to distinguish between the Father, Son, and Holy Spirit. The Trinity is not three gods it is as hisway tried to show in his metaphor one God in three persons or personalities. There is no way you can escape the truth of the Trinity without denying the inerrancy of the NT.
BTW, Kingzson I notice all you are doing is being critical without offering to respond to my last post.
P.S. I have studied history for decades. Modalism has always been viewed as a heretical teaching and does not match God’s revealed truth. Maybe you should study the roots of Gnosticism and how Greek logic violates Hebrew theology then just maybe you will come to understand Christianity whose roots are Hebrew not Greek.