Whoever does not love does not know God, because God is love.
He also sets in opposition to this, according to his usual manner, the contrary clause, that there is no knowledge of God where there is no love. And he takes as granted a general principle or truth, that God is love, that is, that his nature is to love men.
Love descends from heaven itself, it is God's nature and the fruit of His Spirit. Whoever loves with genuine holy affection is born of God and knows Him truly. But whoever loves not, knows not God; such a soul shows by its very coldness that true knowledge of the divine nature has no dwelling place within it.
AI summary
Commenting on 1 John 4:7-13
He that loveth not, knoweth not God,.... If a man loves not the children of God, those that are born of him, he does not know, so as to love God, the Father of them; for to pretend love to God, the begetter of them, whom he sees not, and not love those who are begotten by him, and are visible objects of respect, is...