Christ in His humanity was begotten by God in His resurrection to be the firstborn Son of God (Acts 13:33; Rom. 8:29b). John 1:18 says that Christ is the only begotten Son, who is in the bosom of the Father. In His glory in eternity past, He was the only begotten Son of God. Since He was the Son of God, why did He need to be begotten of God? This was because God needed a firstborn Son.
Christ was the Son of God in eternity past, but He became flesh (John 1:14). His flesh was human, not divine. This human part was surely not related to the divine sonship. His human part had to be begotten of God. For this purpose, I invented a new word—"sonized." Christ's humanity had to be sonized in His resurrection. In His resurrection, He brought His humanity into divinity, making this humanity something divine. Christ in His humanity was sonized, begotten by God, in His resurrection.
All the believers of Christ were regenerated by God the Father through the resurrection of Christ (1 Pet. 1:3). In His resurrection, we all were begotten by God to be His many sons. The firstborn Son of God and the many millions of sons of God were begotten at the same time in one "delivery." I once read of a woman who had seven children in one delivery, but the delivery of Christ's resurrection delivered a countless number of sons of God.
We need to remember that the resurrection of Christ produced three big matters: the life-giving Spirit, the firstborn Son of God, and the many sons of God. The life-giving Spirit, the firstborn Son, and the many sons of God are altogether for the Body of Christ, which is the organism of the Divine Trinity.