If the Son of God already existed before his incarnation, then he must have already been perfect, but how do you explain this passage? :And the Messiah increased in wisdom and in greatness and in favor with God and men.
Your question ASSUMES that the Son of God did not exist eternally before His incarnation. Which shows that you are really ignorant about the Scriptures. I already told you to read, study, digest, and believe the first chapter of John.
AND YOU IGNORED MY ADVICE. Hence these questions and a new thread wasting your time and everyone else's. So listen up and learn:
1. The Son of God is called "the Word of God" in John 1:1.
2. The Word of God is also called "God" in the same verse.
3. By definition God is eternal, therefore the Word of God is also eternal.
4. Therefore the eternal Word of God is also called "the ONLY BEGOTTEN Son of God" in the same chapter. This is a unique Father-Son relationship which has nothing to do with human begetting.
Therefore the Son of God is also eternal.
5. Now when we come to the incarnation, the Son of God came to earth as Jesus of Nazareth. He was fully human and fully divine at one and the same time. But in His humanity, He began as a babe, matured as a child, and then became a Man. Thus
"And Jesus increased in wisdom and stature, and in favour with God and man." (Luke 2:52)
6. He did NOT become the Son of God at this time, since He was
already the eternal Son of God. But He did become the Son of Man, and generally referred to Himself as the Son of Man.