Jesus being the Son of God is talking about his spiritual birth, which is eternal, not created. The humanity of Jesus began in Bethlehem 2000 years ago.
In the letter to the Corinthian church, Paul explains that those in the flesh (humanity) are sons of Adam, and in him are condemned as a result of his disobedience.
Those who are in Christ are Sons of God, because they are saved and made righteous as a result of his obedience.
Therefore if Jesus is not the Son of God, but a son of Adam, he's just as doomed as everyone else, and the bible would make no sense at all.