It seems to me that when God plans for something glorious to occur to glorify Him, He instills a spirit in it and designates it for a predestined moment when it will manifest and bring that glory into existence. The spirit that was meant to bring Christ into existence existed before Abraham was born, had glory, and was with God before the world began. God set apart this spirit to be with Him and, at the predetermined time, to be revealed as the Christ, in a human body, as the Son of God.
