But he that keepeth his word, in him in very deed the charity of God is perfected; and by this we know that we are in him.

“"In this we know that we are in Him, if in Him we be perfected." Perfected in love, he calls them: what is perfection of love? To love even enemies, and love them for this end, that they may be brethren. For not a carnal love ought ours to be. To wish a man temporal weal, is good; but though that fail, let the soul be safe. Dost thou wish life to any that is thy friend? Thou doest well. Dost thou rejoice at the death of thine enemy? Thou doest ill. But haply both to thy friend the life thou wishest him is not for his good, and to thine enemy the death thou rejoicest at hath been for his good. It is uncertain whether this present life be profitable to any man or unprofitable: but the life which is with God without doubt is profitable. So love thine enemies as to wish them to become thy brethren; so love thine enemies as that they may be called into thy fellowship. For so loved He who, hanging on the cross, said, "Father, forgive them, for they know not what they do." For he did not say, Father let them live long, me indeed they kill, but let them live. He was casting out from them the death which is for ever and ever, by His most merciful prayer, and by His most surpassing might.”

“But whoso keepeth his word,.... Either the word of the Gospel, and the truths of it, who receives it in love, cordially embraces and retains it, and will by no means part with it, but holds it fast, and stands fast in it; or the precepts and ordinances of the word, who loves these, and esteems them above fine gold, and concerning all things to be right, and observes them as they should be: in him verily is the love of God perfected: not the love wherewith God loves him, for that is perfect in himself, and admits of no degrees, and cannot be more or less in his heart, and is entirely independent of the obedience of men, or any works of theirs; it is true indeed the manifestations of this love to the saints are imperfect, and may be more and greater, and greater manifestations of love are promised to such that love Christ, and keep his commandments, Joh 14:21; but here it is to be understood not actively, but passively, of the love wherewith God is loved by his people; and intends not the absolute perfection of it in them, in whom it often waxes cold, and is left, or the fervour of it abated, but the sincerity and reality of it; for by keeping the word of God, both his truths and his ordinances, it is clearly seen that their love to him is without dissimulation, and is not in tongue only, but in deed and in truth:, now it is not the keeping of the word of God that causes this love, or makes it perfect or sincere, for it is a fruit of the Spirit, and is owing to the grace of God; but love, on the other hand, is the cause of keeping of the word; and the latter being a consequent and an effect of the former, is the evidence of it, of the truth and sincerity of it: hereby know we that we are in him: in Christ, not merely nominally, or by profession, as all that name the name of Christ, and are in a Gospel church state, may be said to be; but really, first secretly, through the love of Christ, the election of God, and the covenant of grace, and then openly, in conversion and the effectual calling, through believing in Christ, when the saints appear to be in him as branches in the vine; and which is known by their fruits, as here, by keeping the word, and doing the commandments of Christ, which do not put a man into Christ, but only show that he is there; for a man's being in Christ is owing to the grace of God; this is the first thing done in grace, Co1 1:30.”

“But whoso keepeth his word - Conscientiously observes his doctrine, the spirit and letter of the religion of Christ. Is the love of God perfected - The design of God's love in sending Jesus Christ into the world to die for the sin of man τετελειωται, is accomplished, in that man who receives the doctrine, and applies for the salvation provided for him. This seems to be the meaning of the apostle. That we are in him - That we have entered into his spirit and views, received his salvation, have been enabled to walk in the light, and have communion with him by the Holy Spirit.”

“Not merely repeating the proposition, Jo1 2:3, or asserting the merely opposite alternative to Jo1 2:4, but expanding the "know Him" of Jo1 2:3, into "in Him, verily (not as a matter of vain boasting) is the love of (that is towards) God perfected," and "we are in Him." Love here answers to knowledge in Jo1 2:3. In proportion as we love God, in that same proportion we know Him, and vice versa, until our love and knowledge shall attain their full maturity of perfection. his word--His word is one (see on Jo1 1:5), and comprises His "commandments," which are many (Jo1 2:3). hereby--in our progressing towards this ideal of perfected love and obedience. There is a gradation: Jo1 2:3, "know Him"; Jo1 2:5, "we are in Him"; Jo1 2:6, "abideth in Him"; respectively, knowledge, fellowship, abiding constancy. [BENGEL].”