1 John 4:8 (BSB)

Whoever does not love does not know God, because God is love.

From 1 John 4. Also in the ESV.

Commentary on 1 John 4:8

• John Calvin (Reformed), Calvin's Commentaries on 1 John 4:8: 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.
• Matthew Henry (Presbyterian), Matthew Henry's Complete Commentary on 1 John 4:7-13: As the Spirit of truth is known by doctrine (thus spirits are to be tried), it is known by love likewise; and so here follows a strong fervent exhortation to holy Christian love: Beloved, let us love one another, Jo1 4:7.
• John Gill (Reformed Baptist), Exposition of the Old and New Testaments on 1 John 4:8: 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...
• Albert Barnes (Presbyterian), Barnes' New Testament Notes on 1 John 4:8: Verse 8. He that loveth not, knoweth not God. Has no true acquaintance with God; has no just views of him, and no right feelings towards him. The reason for this is implied in what is immediately stated, that "God is love," and of course if they have no love reigning in their hearts they cannot pretend to be like him. For God is love.