1 John 4:14
14And we have seen and testify that the Father has sent his Son to be the Savior of the world.
"The Father sent the Son, he willed his coming into this world."
"For God so loved the world, that he gave his only Son, that whoever believes in him should not perish but have eternal life.
17For God did not send his Son into the world to condemn the world, but in order that the world might be saved through him.
Dr. Bruce Ware:
"Clearly, the Father both consecrated the Son for the very mission he planned for him, and then he sent the Son into the world to fulfill what he had designed. For this to be meaningful, we must understand both the consecration and sending of the Son as happening prior to the incarnation and thus in the design and purpose of God in eternity past."
It is important to understand that the Father sent the Son into the world before the Son was born in Bethlehem, even before He was conceived in the womb of the Virgin Mary. The sending happened in eternity past. In fact, one could say that eternity does not really have a past, present, or future, since eternity speaks of the kind of existence that God has outside of the constraints of time. Time is part of His created order. He is in no way bound by the limits of time.
Therefore, it has always been the will of the Father, - throughout all of time and eternity - with the full agreement of the Son, and the of the Holy Spirit to send the Son as our Savior. The effects of this sending would carry through to all eternity. His coming was at a specific point in time, but the effects of His coming are eternal. In fact, as Matthew Henry points out in his quote above, "He [the Father] willed His [the Son's] coming into the world." The "willing" had to happen before the "coming."
What does it matter? The Son is eternal, as is the Father. They have always had an eternal Father with His eternal Son relationship. The Son did not begin His life when He was conceived by the Holy Spirit in the womb of the Virgin Mary. He is the eternal Son of God, just as the Father is our Eternal Father, and the Holy Spirit is the eternal Spirit of God. It has always been this way, and it always will be, for God in His essence does not and cannot change.
Since the Father is eternal, the Son is also eternal. How can there be an eternal Father if there is no eternal Son?
Of course, there is only One eternal God who has always existed and will always exist in what are called three hypostases - IOW, three persons who are one in essence and will.
The eternal God is your dwelling place, and underneath are the everlasting arms. And he thrust out the enemy before youand said, Destroy.
but has now been disclosed and through the prophetic writings has been made known to all nations, according to the command of the eternal God, to bring about the obedience of faith—