John presented a powerful argument for the identity of Jesus of Nazareth, saying,
This is He who came by water and blood—Jesus Christ;
not only by water, but by water and blood.
And it is the Spirit who bears witness,
because the Spirit is truth.
For there are three that bear witness in heaven:
the Father, the Word, and the Holy Spirit;
and these three are one.
And there are three that bear witness on earth:
the Spirit, the water, and the blood;
and these three agree as one.
Jesus came by water and by blood. He came by water when He was baptized, at which time the Spirit descended upon the Lord, and He ministry began. He came by blood when He was crucified, shedding His blood and He said, “It is finished,” ending His ministry. Water began his ministry and blood ended His ministry.
Moreover, the Spirit bears witness of Jesus as the Christ and as the Son of God. The Spirit fell upon Him at His baptism, was with Him during His ministry, and fulfilled all prophecies at His death. The Spirit is truth. Is there a Spirit? Yes, and He is the truth detector. If Jesus was not the Christ and not the Son of God, the Spirit would have said so. However, He testifies that Jesus is the Christ, the Son of the living God.
There is a question about verse 7 in the Old King James and New King James Versions. It is believed that a scribe who was writing the Latin added what the King James has for verse 7.
“It is a matter of record that it appears first, not in the original Greek of the New Testament, but in the Latin translation. The earliest manuscript in which it appears in Greek is a copy made in the sixteenth century” (Clinton R. Gill).
“The passage is absent from every known Greek manuscript except four, and these contain the passage in what appears to be a translation from a late recension of the Latin Vulgate. These four manuscripts are ms. 61, a sixteenth century manuscript…ms. 88, a twelfth century manuscript…ms. 629, a fourteenth or fifteenth century manuscript…and ms. 635, an eleventh century manuscript which has the passage written in the margin by a seventeenth century hand. The passage is quoted by none of the Greek Fathers, who, had they known it, would most certainly have employed it in the Trinitarian controversies…Its first appearance in Greek is in a Greek version of the (Latin) Acts of the Lateran Council in 1215” (Bruce M. Metzger, A Textual Commentary on the Greek New Testament).
All of this evidence against it is powerful when it is considered that we have hundreds of ancient manuscripts of the Greek New Testament, and thousands when all Greek New Testament manuscripts are considered, that is, including what are called modern.
So then, the three witnesses are: the Spirit, the water, and the blood. There is no disagreement among these three, but perfect harmony. They all verify that Jesus is of God.