John says in 1 John 3:11, that we falsely boast of love to God, except we love our brethren; and this is most true. But he now takes love to the brethren as a testimony by which we prove that we love God. In short, since love so regards God, that in God it embraces men, there is nothing strange in this, that the Apostle, speaking of love, should refer at one time to God, at another to the brethren; and this is what is commonly done in Scripture. The whole perfection of life is often said to consist in the love of God; and again, Paul teaches us, that the whole law is fulfilled by him who loves his neighbor, (Romans 13:8;) and Christ declares that the main points of the law are righteousness, judgment, and truth. (Matthew 23:23.) Both these things are true and agree well together, for the love of God teaches us to love men, and we also in reality prove our love to God by loving men at his command. However this may be, it remains always certain that love is the rule of life. And this ought to be the more carefully noticed, because all choose rather almost anything else than this one commandment of God.
To the same purpose is what follows, and there is no occasion of stumbling in him — that is, in him who acts in love; for, he who thus lives will never stumble. (65)
(65) Literally, “and to him there is not a stumblingblock;” that is, nothing that causes him to stumble or fall. He is not like him mentioned in the next verse, who “ walks in darkness and knows not whither he goeth.” The sentence seems to have been taken from Psalms 119:165, with this only difference, that it is “ to them,” instead of “ to him.” There is in the Sept no preposition, but in Hebrew the preposition “to” is used; and ἐν has sometimes this meaning in the New Testament. See Colossians 1:23; 1 Thessalonians 4:7. — Ed.