Expositor's Bible Commentary Commentary 1 John 5:9

"If we receive the witness of men, the witness of God is greater: for the witness of God is this, that he hath borne witness concerning his Son." — 1 John 5:9 (ASV)

The divine witness is not limited to the Spirit but includes the witness of the Father. His witness is greater than the authenticated witness of a human being because of the nature of the one who gives it and of its greater trustworthiness (cf. Jn 5:36-37). It was his voice that confirmed that Jesus’ “passion” was an act in which God would glorify himself . So also it is God’s own voice that is being heard again in the threefold witness.