It is here signified how satisfying a knowledge and certainty sincere Christians had, that Christ was indeed come, by that blessed effect they found upon themselves, viz. a clear and lively light shining, by his procurement and communication, into their minds, whereby they had other apprehensions, more vivid and powerful than ever before, of the true God, as 1 Thessalonians 17:3, so as thereby to be drawn into union with him, and to be in him: or, which in effect is the same thing, (so entire is the oneness between the Father and the Son), we are in his Son Jesus Christ, who also is the true God, as 1 Thessalonians 1:1, and eternal life, as he is called, 1 John 1:2.
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.