The Trinity is the foundation of the gospel

In the Trinity, the Father loves and adores his Son (John 3:35). And the Son honors and obeys his Father (John 14:31). The Father sends forth his Son to the cross that the Son might be lifted up and glorified, because the Father loves the Son (John 17:24). The Son willingly and joyfully goes to the cross that the Father might be glorified, because the Son loves the Father (John 8:49). The Holy Spirit opens the hearts of men that they may believe in the Son and give him glory, because the Spirit loves the Son (John 16:14).

Russian icon of the Old Testament Trinity by Andrei Rublev (1425)

In the drama of salvation, each person of the Trinity serves and lifts up the other persons, because at the heart of God is servanthood.  For love seeks not its own, but the beloved.  Therefore, God is love (1 John 4:8).  This eternal love within the Trinity overflows to humanity in creation, and comes to a climax in the redeeming death of the Son on a Roman cross. There is no salvation without the Trinity. These are mysterious too wonderful to behold. We will look upon and marvel at this love for all eternity and never exhaust its depths.

I preached on this in a sermon, “Introduction to the Trinity.” You can listen to it here: