In this, the love of God was manifest among us, that God sent His only begotten Son into the world in order that through Him we should live, 1 John 4:9.
A single act of love by God the Father sent God the Son into the world. Father and Son relate to position and relationship, not genealogy. God the Son was not born or brought into existence by God the Father. They, along with God the Spirit, have always existed as a single divine Being (Deuteronomy 6:4; Isaiah 45:5).
God the Son wrapped Himself in flesh so that all those who believe in Him could possess eternal life (Philippians 2:6–8; 1 John 5:12).
This is a true act of love. God the Father, in a single act of love towards the world, gave the world the very things it needed most: a Savior. “For in this manner the God loved the world so that He gave His unique one of a kind Son in order that all those who believe should not perish but have eternal life.” (John 3:16).