1 John 4:15

15 whoever may confess that Jesus is the Son of God, God in him doth remain, and he in God;

1 John 4:15 Meaning and Commentary

1 John 4:15

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 Romans 10:10 ) .

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.

1 John 4:15 In-Context

13 in this we know that in Him we do remain, and He in us, because of His Spirit He hath given us.
14 And we -- we have seen and do testify, that the Father hath sent the Son -- Saviour of the world;
15 whoever may confess that Jesus is the Son of God, God in him doth remain, and he in God;
16 and we -- we have known and believed the love, that God hath in us; God is love, and he who is remaining in the love, in God he doth remain, and God in him.
17 In this made perfect hath been the love with us, that boldness we may have in the day of the judgment, because even as He is, we -- we also are in this world;
Young's Literal Translation is in the public domain.