“This is he that came by water and blood, even Jesus Christ; not by water only, but by water and blood. And it is the Spirit that beareth witness, because the Spirit is truth.”
King James Version (KJV)
5:6 This is he - St. John here shows the immovable foundation of that faith that Jesus is the Son of God; not only the testimony of man, but the firm, indubitable testimony of God. Who came - Jesus is he of whom it was promised that he should come; and who accordingly, is come. And this the Spirit, and the water, and the blood testify. Even Jesus - Who, coming by water and blood, is by this very thing demonstrated to be the Christ. Not by the water only - Wherein he was baptized. But by the water and the blood - Which he shed when he had finished the work his Father had given him to do. He not only undertook at his baptism to fulfil all righteousness, but on the cross accomplished what he had undertaken; in token whereof, when all was finished, blood and water came out of his side. And it is the Spirit who likewise testifieth - Of Jesus Christ, namely, by Moses and all the prophets, by John the Baptist, by all the apostles, and in all the writings of the New Testament. And against his testimony there can be no exception, because the Spirit is truth - The very God of truth.
1Jo 5:6 This is he that came by water and blood, [even] Jesus Christ. The subject of faith in Christ calls out a statement concerning some of the constantly testifying witnesses of Christ. The water and the blood refer primarily to the baptism that revealed him at the beginning of his earthly ministry and the blood which he shed at its close. John came baptizing in order that Christ should be made manifest (Joh 1:31). It was while in the waters of the Jordan that Christ was manifested and anointed. On the cross flowed the water and the blood (Joh 19:34). Two rites, both monumental institutions, hence both of them witnesses, testify of him. We are baptized into his death (Ro 6:1-3); the Lord's Supper points to his shed blood. Not by water only, but by water and blood. The revelation of Christ in water at the baptism does not stand alone; Calvary came also with its shedding of blood. It is the Spirit that beareth testimony. Witness is usually borne in words. The Spirit which descended on the apostles on Pentecost bore witness with mighty power that the crucified Jesus was Lord and Christ (Ac 2:4 4:31 5:32).