Verse 15. - Whosoever confesseth ο{ς α}ν ὁμολογήση. This rendering seems preferable to "whosoever shall confess" or "shall have confessed." The exact meaning is, "Whosoever has once for all taken up the position of confessing." Verse 14 gave the case of the apostles; this gives that of those who accept their witness. In the next verse we have that of both together.

4:14-21 The Father sent the Son, he willed his coming into this world. The apostle attests this. And whosoever shall confess that Jesus is the Son of God, God dwelleth in him, and he in God. This confession includes faith in the heart as the foundation; makes acknowledgment with the mouth to the glory of God and Christ, and profession in the life and conduct, against the flatteries and frowns of the world. There must be a day of universal judgment. Happy those who shall have holy boldness before the Judge at that day; knowing he is their Friend and Advocate! Happy those who have holy boldness in the prospect of that day, who look and wait for it, and for the Judge's appearance! True love to God assures believers of God's love to them. Love teaches us to suffer for him and with him; therefore we may trust that we shall also be glorified with him, 2Ti 2:12. We must distinguish between the fear of God and being afraid of him; the fear of God imports high regard and veneration for God. Obedience and good works, done from the principle of love, are not like the servile toil of one who unwillingly labours from dread of a master's anger. They are like that of a dutiful child, who does services to a beloved father, which benefit his brethren, and are done willingly. It is a sign that our love is far from perfect, when our doubts, fears, and apprehensions of God, are many. Let heaven and earth stand amazed at his love. He sent his word to invite sinners to partake of this great salvation. Let them take the comfort of the happy change wrought in them, while they give him the glory. The love of God in Christ, in the hearts of Christians from the Spirit of adoption, is the great proof of conversion. This must be tried by its effects on their temper, and their conduct to their brethren. If a man professes to love God, and yet indulges anger or revenge, or shows a selfish disposition, he gives his profession the lie. But if it is plain that our natural enmity is changed into affection and gratitude, let us bless the name of our God for this seal and earnest of eternal happiness. Then we differ from the false professors, who pretend to love God, whom they have not seen, yet hate their brethren, whom they have seen.Whosoever shall confess that Jesus is the Son of God,.... The only begotten of the Father; that he is not a mere man, as the Jews, and Ebion and Cerinthus said, but a divine person, equal with the Father; which contains all that relates to the dignity of his person, and his fitness for his office as a Saviour, and which was the test of faith in those times, and the grand article of belief: not that a bare assent to this had what followed annexed to it; for the devils believed and owned that Jesus was the Son of God; and so might, and did, unregenerate persons, as the centurion at the cross of Christ, who know nothing what communion with God is; but this confession is such as is attended with a believing in Christ from the heart unto righteousness, life, and salvation, and a cheerful obedience to his ordinances and commands, from a principle of love to him, and faith in him, things not to be found in devils and carnal men; see Romans 10:9.

God dwelleth in him, and he in God; See Gill on 1 John 4:13; this should encourage to an open and hearty confession of Christ as the Son of God, and Saviour of sinners, and to a public profession of his name, and faith in him, and an holding it fast without wavering.