Many Christians are unaware that philosophical, mystical ideas invaded the church from the second century onwards via the "Church Fathers," who were steeped in pagan philosophy and laid the foundation of the creeds now called "orthodox." In several articles you from the Belgian Biblestudents you shall be able to read more about it. There and on a.o. the writing of Anthony Buzzard you shall be able to find that 'The seed of Trinitarian doctrine' was planted in the thinking of Justin Martyr, the second century Christian apologist who "found in Platonism the nearest approach to Christianity and felt that no break was required with its spirit and principles to pass into the greater light of Christian revelation."
The New Testament never suggests that the phrase ‘Son of God’ just means ‘God.’ [Yet evangelicalism and certain major groups insists on that equation if one is to be considered a Christian!]
But in the world we do find lots of serious lovers of God who accept the Nazarene Jew Yeshua or Jesus as the promissed Saviour. For them however he is the "man Messiah," the one Mediator between God and man (1 Tim. 2:5). As for the apostle Paul those believers in only One God take it that "To us Christians there is one God, the Father, and one Lord Messiah" (1 Cor. 8:4-6). (Note carefully Paul’s definition of the One God.)
Human beings in Hebrew thought do not exist consciously before they are born. In the Holy Scriptures we do also find no preexistence of souls. The notion that Jesus was really alive and conscious before his birth in Bethlehem is also a very unJewish idea.
As you could already find in our other writings on the understanding of Hebrew writings, we do have to take that language as our guide and not our modern thinking or the Greek philosophy. E.C. Dewick rightly notes in his Primitive Christian Eschatology, The Hulsean Prize Essay for 1908, Cambridge University Press, 1912: "When the Jew said something was ‘predestined,’ he thought of it as already ‘existing’ in a higher sphere of life. The world’s history is thus predestined because it is already, in a sense, preexisting and consequently fixed. This typically Jewish conception of predestination may be distinguished from the Greek idea of preexistence by the predominance of the thought of ‘preexistence’ in the Divine purpose."
All is foreordained in God’s great Plan and so did God created the opportunity to get a Saviour out of the tribe of David. It is not becaus God knows everything already before hand that because Jesus who came up in the thought of God before the world was created, that Jesus actually really came into existence before everything was created. The Messiah himself was foreknown, not just his death for our sins but the person Messiah himself (1 Pet. 1:20). Peter uses the same word to describe the "existence" of the Son of God in God’s plan as he did to describe the "existence" of the Christian church (v. 2).
All Jews who looked forward to the Messiah expected a human person, not an angel, much less God Himself! Though the Jews had not understood that the Messiah was to be born supernaturally, even this miraculous begetting was in fact predicted (Isa. 7:14; Matt. 1:23). A "pre-human" Messiah, however, is nowhere suggested. The Son of God "came into existence" from a woman and from the seed of David (Rom. 1:4; Gal. 4:4).(Note that for Arians and Trinitarians, who think that Jesus was begotten in eternity long before his conception/begetting in Mary, that would have been a second begetting.)
Read more about Foreordination Rather than Literal Preexistence : The Nature of Preexistence in the New Testament by Anthony Buzzard
Colossians 1:15-20: Preexistence or Preeminence? by William WachtelThe Nature of Preexistence in the New Testament or Preexistensens natur i Nya testamentet (Swedish)Who Is Jesus? God, or Unique Man? or Wie is Jesus? God, of Unieke Mens? (Afrikaans)