In Delighting in the Trinity, Michael Reeves discusses how God's triune-ness and God's love go hand in hand. God has been loving within the trinity since eternity. The Father loves the Son and the Spirit; the Son loves the Father and the Spirit; the Spirit loves the Father and the Son. God is love, and always has been love and loving.
With this in mind, Reeves brings up the idea of humanity's fall; part of that picture is the idea of Adam and Eve directing the love they had for God to something other than God: ourselves and anything but God. To this catastrophic event, God responded in love. Reeves writes,
Astonishingly, it was this very rejection of God that drew forth the extreme depths of his love. In his response to sin we see deeper than ever into the very being of God. “Whoever does not love does not know God, because God is love. This is how God showed his love among us: He sent his one and only Son into the world that we might live through him. This is love: not that We loved God, but that he loved us and sent his Son as an atoning sacrifice for our sins” (1 Jn 4:8-10).
The God who is love definitively displays that love to the World by sending us his eternally beloved Son to atone for our sin. (68)And so, it is in the cross-God's remedy for sin-that we see God's love poured out most profoundly and prolifically. Reeves continues:
Without the cross, we could never have imagined the depth and seriousness of What it means to say that God is love. “This is how we know What love is: Jesus Christ laid down his life for us” (1 Jn 3:16). On the cross we see the great holiness of God’s love, that the light of his pure love will destroy the darkness of sin and evil. On the cross we see the intensity and strength of his love, that it is not an insipid thing at all, but majestically strong as it faces death, battles evil and gives life. For Christ was not bound against his will and dragged to a crucifixion he did not choose. Nobody could take his life from him, he said. “I lay it down of my own accord. I have authority to lay it down and authority to take it up again. This command I received from my Father” (Jn 10:18). Jesus’ self-giving love is entirely unconstrained and free. It comes, not from any necessity, but entirely out of who he is, the glory of his Father. Through the cross we see a God who delights to give himself.Thus, the triune God who has been love since before creation, demonstrates that He is love most gloriously in the cross of Christ. I highly recommend this book by Michael reeves!