And we know that the son of God is come, &c.— "And from all the undoubted proofs before insisted on, we certainly know that Jesus, the Son of God, has assumed human nature, and actually came into this lower world to put away sin by the sacrifice of himself (Hebrews 9:26.); and we know by our own happy experience, that he has not only given us an external revelation in his word, but has enlightened the eyes of our minds by an internal operation of his Spirit, that we might have a saving knowledge of him who is Truth itself: and we are vitally united to him, who, in all that he has said, is the true and faithful witness (Revelation 1:5.), even Jesus Christ the eternal Son of God. This Jesus (ουτος), in his original nature, is the only living and true God, together with the Father and the Spirit; and he is the purchaser and giver of spiritual and eternal life to all his faithful saints."
Related Commentaries of 1 John 5:20
1 John 5:20
20 And we know that the Son of God is come, and hath given us an understanding, that we may know him that is true, and we are in him that is true, even in his Son Jesus Christ. This is the true God, and eternal life.