That God is triune, “changes the flavor and meaning of every word we use about him” writes Michael Reeves. For instance, if God were not triune, his wrath would be “hideous,” but since God, as Trinity, is essentially loving,
his wrath is not something that sits awkwardly next to his love. Nor is it something unrelated to his love. God is angry at evil because he loves. Isaiah speaks of the pouring out of God’s wrath as his “strange work,” his “alien task” (Is 28:21), because it is not that God is naturally angry, but that evil provokes him: in his pure love, God cannot tolerate evil. That makes complete sense to me as a father: if I could twiddle my thumbs and yawn while my daughters suffered, it would prove I didn’t really love them; but precisely because I so love them I hate the thought of anything evil befalling them. How much more is it so with the Father of lights, in whom there is no darkness at all. Love cares, and that means it cannot be indifferent to evil. “Love must be sincere. Hate what is evil; cling to what is good” (Rom 12:9) Only such love is sincere.
…Were God not triune, and so not eternally love, his wrath would make him look like an overgrown, foot-stamping toddler, a fight picking bully or a merciless sultan. Think of the hormonal outbursts of the gods of ancient Greece and Rome. But with the God who is eternally love, his anger must rise from that love. Thus his anger is holy, set apart from our temper-tantrums; it is how he in his love reacts to evil. The Father loves his Son, and so hates sin, which ultimately is rejection of the Son; he love his children, and so hates their being oppressed; he loves his world, and so hates all evil in it. Thus in his love he roots out sin in his people, even disciplining them that they might be freed from their captivity to it. In his love he is patient with us. And in his love he promises finally to destroy all evil as light destroys darkness.
The wrath of the triune God is exactly the opposite of a character blip or a nasty side in him. It is the proof of the sincerity of his love, that he truly cares. His love is not mild-mannered and limp; it is livid, potent and committed. And therein lies our hope: through his wrath the living God shows that he is truly loving, and through his wrath he will destroy all devilry that we might enjoy him in a purified world, the home of righteousness.
Quoting from Delighting in the Trinity: An Introduction to the Christian Faith.