1 John 3:15-18
14. We know that we have passed from death unto life, because we love the brethren. He that loveth not his brother abideth in death.
14. Nos scimus quod transierimus a morte in vitam, quia diligimus fratres: qui non diligit fratrem, manet in morte.
15. Whosoever hateth his brother is a murderer: and ye know that no murderer hath eternal life abiding in him.
15. Omnis qui odit fratrem suum, homicida est; et nostis quod omnis homicida, non habet vitam aeternam in se manentem.
16. Hereby perceive we the love of God, because he laid down his life for us: and we ought to lay down our lives for the brethren.
16. In hoc cognoscimus charitatem, quod ille pro nobis animam suam posuit: et nos debemus pro fratribus animas ponere.
17. But whoso hath this world's good, and seeth his brother have need, and shutteth up his bowels of compassion from him, how dwelleth the love of God in him?
17. Si quis habeat victum mundi, et videat fratrem suum egentem, et claudat viscera sua ab eo, quomodo charitas Dei in ipso manet?
18. My little children, let us not love in word, neither in tongue; but in deed and in truth.
18. Filioli mei, ne diligamus sermone, neque lingua, sed opere et veritate.
14 We know. He commends love to us by a remarkable eulogy, because it is an evidence of a transition from death to life. It hence follows that if we love the brethren we are blessed, but that we are miserable if we hate them. There is no one who does not wish to be freed and delivered from death. Those then who by cherishing hatred willingly give themselves up to death, must be extremely stupid and senseless. But when the Apostle says, that it is known by love that we have passed into life, he does not mean that man is his own deliverer, as though he could by loving the brethren rescue himself from death, and procure life for himself; for he does not here treat of the cause of salvation, but as love is the special fruit of the Spirit, it is also a sure symbol of regeneration. Then the Apostle draws an argument from the sign, and not from the cause. For as no one sincerely loves his brethren, except he is regenerated by the Spirit of God, he hence rightly concludes that the Spirit of God, who is life, dwells in all who love the brethren. But it would be preposterous for any one to infer hence, that life is obtained by love, since love is in order of time posterior to it.
The argument would be more plausible, were it said that love makes us more certain of life: then confidence as to salvation would recumb on works. But the answer to this is obvious; for though faith is confirmed by all the graces of God as aids, yet it ceases not to have its foundation in the mercy of God only. As for instance, when we enjoy the light, we are certain that the sun shines; if the sun shines on the place in which we are, we have a clearer view of it; but yet when the visible rays do not come to us, we are satisfied that the sun diffuses its brightness for our benefit. So when faith is founded on Christ, some things may happen to assist it, still it rests on Christ's grace alone.
15 Is a murderer To stimulate us still more to love, he shews how detestable before God is hatred. There is no one who dreads not a murderer; nay, we all execrate the very name. But the Apostle declares that all who hate their brethren are murderers. He could have said nothing more atrocious; nor is what is said hyperbolical, for we wish him to perish whom we hate. It does not matter if a man keeps his hands from mischief; for the very desire to do harm, as well as the attempt, is condemned before God: nay, when we do not ourselves seek to do an injury, yet if we wish an evil to happen to our brother from some one else, we are murderers.
Then the Apostle defines the thing simply as it is, when he ascribes murder to hatred. Hence is proved the folly of men, that though they abominate the name, they yet make no account of the crime itself. Whence is this? even because the external face of things engrosses our thoughts; but the inward feeling comes to an account before God. Let no one therefore extenuate any more so grievous an evil. Let us learn to refer our judgments to the tribunal of God.
16 Hereby perceive we, or, By this we know. He now shews what true love is; for it would not have been enough to commend it, unless its power is understood. As an instance of perfect love, he sets before us the example of Christ; for he, by not sparing his own life, testified how much he loved us. This then is the mark to which he bids them to advance. The sum of what is said is, that our love is approved, when we transfer the love of ourselves to our brethren, so that every one, in a manner forgetting himself, should seek the good of others. 
It is, indeed, certain, that we are far from being equal to Christ: but the Apostle recommends to us the imitation of him; for though we do not overtake him, it is yet meet, that we should follow his steps, though at a distance. Doubtless, since it was the Apostle's object to beat down the vain boasting of hypocrites, who gloried that they had faith in Christ though without brotherly love, he intimated by these words, that except this feeling prevails in our hearts, we have no connection with Christ. Nor does he yet, as I have said, set before us the love of Christ, so as to require us to be equal to him; for what would this be but to drive us all to despair? But he means that our feelings should be so formed and regulated, that we may desire to devote our life and also our death, first to God, and then to our neighbors.
There is another difference between us and Christ, — the virtue or benefit of our death cannot be the same. For the wrath of God is not pacified by our blood, nor is life procured by our death, nor is punishment due to others suffered by us. But the Apostle, in this comparison, had not in view the end or the effect of Christ's death; but he meant only that our life should be formed according to his example.
17 But whose hath this world's good, or, If any one has the world's sustenance. He now speaks of the common duties of love, which flow from that chief foundation, that is, when we are prepared to serve our neighbors even to death. He, at the same time, seems to reason from the greater to the less; for he who refuses to alleviate by his goods the want of his brother, while his life is safe and secure, much less would he expose for him his life to danger. Then he denies that there is love in us, if we withhold help from our neighbors. But he so recommends this external kindness, that at the same time he very fitly expresses the right way of doing good, and what sort of feeling ought to be in us.
Let this, then, be the first proposition, that no one truly loves his brethren, except he really shews this whenever an occasion occurs; the second, that as far as any one has the means, he is bound so far to assist his brethren, for the Lord thus supplies us with the opportunity to exercise love; the third, that the necessity of every one ought to be seen to, for as any one needs food and drink or other things of which we have abundance, so he requires our aid; the fourth, that no act of kindness, except accompanied with sympathy, is pleasing to God. There are many apparently liberal, who yet do not feel for the miseries of their brethren. But the Apostle requires that our bowels should be opened; which is done, when we are endued with such a feeling as to sympathize with others in their evils, no otherwise than as though they were our own.
The love of God Here he speaks of loving the brethren; why then does he mention the love of God? even because this principle is to be held, that it cannot be but that the love of God will generate in us the love of the brethren.  And thus God tries our love to him, when he bids us to love men from a regard to himself, according to what is said in Psalm 16:2,
"My goodness reaches not to thee, but towards the saints who are on the earth is my will and my care."
18. Let us not love in word There is a concession in this first clause; for we cannot love in tongue only; but as many falsely pretend this, the Apostle concedes, according to what is often done, the name of the thing to their dissimulation, though, in the second clause, he reproves their vanity, when he denies that there is reality except in the deed. For thus ought the words to be explained, — Let us not profess by the tongue that we love, but prove it by the deed; for this is the only true way of shewing love. 
 There is no authority for adding of God after love in this verse; nor indeed is it right, for what follows clearly shows that the love of Christ is what is referred to. The antecedent to "he," ("because he laid down," &e.) is "the Son of God" in the 8th verse. The passage may be thus rendered, "By this we know love, that he laid down his own life for us; and we ought to lay down our lives for our brethren." -- Ed.  "The love of God" here is love of which God is the object, that is, love to God. -- Ed.  Beza and others regard "only," or "merely," as understood in the first clause, according to a mode of speaking which often occurs in Scripture, as "Labor not," etc., (John 6:27.) "My dear children, let us love, not only by word, or with the tongue, but by work and in truth." That is, let us not love only by making in words fair promises, or by expressing sympathy with the tongue, but by giving effect to our sympathy by works, and by making our word true, by fulfilling it. Here we find the same arrangement as in many other instances; the "word" has its correspondence in "truth;" and "tongue in "work." It is justly observed by Macknight, that "the Apostle cannot be supposed to forbid our using affectionate speeches to our brethren in distress But he forbiddeth us to content ourselves with these." -- Ed
 "The love of God" here is love of which God is the object, that is, love to God. -- Ed.
 Beza and others regard "only," or "merely," as understood in the first clause, according to a mode of speaking which often occurs in Scripture, as "Labor not," etc., (John 6:27.) "My dear children, let us love, not only by word, or with the tongue, but by work and in truth." That is, let us not love only by making in words fair promises, or by expressing sympathy with the tongue, but by giving effect to our sympathy by works, and by making our word true, by fulfilling it. Here we find the same arrangement as in many other instances; the "word" has its correspondence in "truth;" and "tongue in "work." It is justly observed by Macknight, that "the Apostle cannot be supposed to forbid our using affectionate speeches to our brethren in distress But he forbiddeth us to content ourselves with these." -- Ed