John Gills Exposition of the Bible Commentary

Verse 15 (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 .

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.

- John Gills Exposition of the Bible Commentary