If anyone says, “I love God,” but hates his brother, he is a liar. For anyone who does not love his brother, whom he has seen, cannot love God, whom he has not seen.
But this love cannot exist, except it generates brotherly love. Hence he says, that they are liars who boast that they love God, when they hate their brethren. But the reason he subjoins seems not sufficiently valid, for it is a comparison between the less and the greater: If, he says, we love not our brethren whom we see, much less can we love God who is invisible.
The apostle, having thus excited and enforced sacred love from the great pattern and motive of it, the love that is and dwells in God himself, proceeds to recommend it further by other considerations; and he recommends it in both the branches of it, both as love to God, and love to our brother or Christian neighbour. I.
Commenting on 1 John 4:17-21
And this commandment have we from him,.... Either "from God", as the Alexandrian copy and the Vulgate Latin version read; and that to love the brethren is a commandment of God, is clear from Jo1 3:23; or from Christ, for it is also a command of his, even his new commandment, which he has given, and his people have received from him: that he who...