The Son is sent to be savior of the world (1 John 4:14). And it’s only as the only-begotten Son that He can be Savior. This is true in the usual sense that Jesus is the “contact point” between God and man.

But it’s also true in a more subtle sense. Jesus saves us by communicating life (1 John 4:9). But is life something that can be communicated? Is life something that can flow out from the Father? Is life something that can be shared? Yes, of course: It always has, because the Father has never been without His Son; the life of the Father has always been shared with His Son. Life can be distributed to creation only because there is an only-begotten Son.