But you keep telling he did not become the Son of God and instead became a man.
The Son of God didn't become a Man but rather The Son of God is Man from the New Creation in Whom His elect are transformed from old to new creation.
But first we must define Who is the MONOGENES SON.
All of Christendom don't understand by how The Son was Begotten.
God is utter transcendent (beyond space, matter and time). But then His creatures have no access to Him. He can't be seen nor heard. He would have been a mystery had He not become part of His own creation (in space, matter and time).
Everyone assumes here that God is accessible. If they think thus, they are miserable creature with no knowledge of God whatsoever and are in path of destruction.
The Son of God proceeded forth from the innermost Being of God bearing the image of His substance. That's why His birth had to be unique which never happened before. He bore the DNA of His Father being born of water and blood (elements of the womb). That's why The Virgin was chosen for His Birth.
Even Israel as corporate body was considered the unfaithful wife of Yahuah Elohim. Yahuah sent her away with the certificate of divorce and dispersed her until she was purified to be a chaste virgin bethroed to Messiah.
Rev 12 speaks of the same woman Israel giving birth to the Male Child.
The Male Child purified the Woman as The Woman is saved by Him in her bearing.
It's The same Son of God Who reveals The Father (Transcendent) without Whom all creatures would have been in hopeless situation.
The Father is the Sending source and The Son is the Receiving End - The First and The Last.
The Father and The Son are not two different Persons but two distinct realms - Transcendent and Immanent creation. Neither are Father and Son Names of God Persons.
What Unitarians and Trinitarians fail to understand that The Father and The Son are titles of the same God in two distinct realms - Beyond all Creation and within Creation.
If there is no Receiving End then we are most miserable people just as there would not be a sending end.
No creature has any access to the transcendent God but only The Monogenes Son has because He came from the very Being of God.
Many people don't understand the simplicity of Yahusha Messiah.
By bearing the very image of the invisible God, He is equal WITH God because He is not different from the nature of the Transcendent God. In Him the will of God is executed and fulfilled.
1Tim 6:
14 that you guard the command
b spotlessly, blamelessly, until the appearing of our Master יהושע Messiah,
15 which in His own seasons He shall reveal – the blessed and only Ruler, the Sovereign of sovereigns and Master of masters,
16 who alone has immortality, dwelling in unapproachable light, whom no one has seen or is able to see, to whom be respect and everlasting might. Amĕn.