Matthew Henry Commentary 1 John 5:6-8

"This is he that came by water and blood, [even] Jesus Christ; not with the water only, but with the water and with the blood. And it is the Spirit that beareth witness, because the Spirit is the truth. For there are three who bear witness, the Spirit, and the water, and the blood: and the three agree in one." — 1 John 5:6-8 (ASV)

We are inwardly and outwardly defiled; inwardly, by the power and pollution of sin in our nature. For our cleansing, there is in and by Christ Jesus the washing of regeneration and the renewing of the Holy Spirit. Some think that the two sacraments are referred to here: baptism with water, as the outward sign of regeneration and purifying from the pollution of sin by the Holy Spirit; and the Lord's Supper, as the outward sign of the shedding of Christ's blood, and the receiving Him by faith for pardon and justification. Both these ways of cleansing were represented in the old ceremonial sacrifices and cleansings.

This water and blood include all that is necessary to our salvation. By the water, our souls are washed and purified for heaven and the habitation of saints in light. By the blood, we are justified, reconciled, and presented righteous to God. By the blood, the curse of the law being satisfied, the purifying Spirit is obtained for the internal cleansing of our natures.

The water, as well as the blood, came out of the side of the sacrificed Redeemer. He loved the church and gave Himself for it, that He might sanctify and cleanse it with the washing of water by the word; that He might present it to Himself a glorious church (Ephesians 5:25–27). This was done in and by the Spirit of God, according to the Savior's declaration. He is the Spirit of God and cannot lie.

Three have borne witness to these doctrines concerning the person and salvation of Christ. The Father, repeatedly, by a voice from heaven declared that Jesus was His beloved Son. The Word declared that He and the Father are One, and that whoever has seen Him has seen the Father. And the Holy Spirit, who descended from heaven and rested on Christ at His baptism; who had borne witness to Him by all the prophets; and gave testimony to His resurrection and mediatorial office, by the gift of miraculous powers to the apostles.

But whether this passage is cited or not, the doctrine of the Trinity in Unity stands equally firm and certain. To the doctrine taught by the apostles, respecting the person and salvation of Christ, there were three testimonies.

1. The Holy Spirit. We come into the world with a corrupt, carnal disposition, which is enmity to God. That this is done away by the regeneration and new-creating of souls by the Holy Spirit is a testimony to the Savior.
2. The water: this demonstrates the Savior's purity and purifying power. The actual and active purity and holiness of His disciples are represented by baptism.
3. The blood which He shed: this was our ransom, and this testifies for Jesus Christ; it sealed and finished the sacrifices of the Old Testament. The benefits procured by His blood prove that He is the Savior of the world. No wonder if whoever rejects this evidence is judged a blasphemer of the Spirit of God.

These three witnesses are for one and the same purpose; they agree in one and the same thing.