Philip Schaff's Popular Commentary (4 vols)
1 John 5:6
The Divine Testimony to Jesus Christ as the ground of faith: this is first viewed objectively, as a witness in history; then subjectively, as a witness enjoyed by the believer.
1 John 5:6. This is he that came by water and blood, even Jesus Christ; not in the water only, but in the water and in the blood. And it is the Spirit that beareth witness, because the Spirit is the truth. It must be remembered in the exposition of this difficult passage, first, that it is governed by the idea of testimony, human and Divine, that ‘Jesus is the Christ' (1 John 5:1), and ‘that Jesus is the Son of God' (1 John 5:5); secondly, that the very terms used imply a symbolical meaning underlying the literal, for we cannot understand ‘water' and ‘blood' as pointing to merely historical facts; thirdly, that the apostle has in view the errors of his own time concerning the manifestation of Jesus in the flesh. ‘This Person Jesus Christ' who ‘came' not into the world, but into His Messianic office as the Christ, ‘by water and blood.' There are two leading interpretations of those words. One of them understands by the ‘water' the baptismal institute of John, which inaugurated Jesus into His Christly office, and by the ‘blood' the passion and death. The other regards St. John as fixing his thought upon the mysterious ‘sign' that he beheld after the Saviour's death: when the piercing of His side was followed by the double stream of blood and of water the blood of expiation and the water of life which flowed together as the symbol of one eternal life from the living death of the sacrifice. The latter we hold to as the true meaning. But let us do justice to the former: it runs thus.
The error of antichrist concerning the incarnation of the Son of God has been already condemned. The witness borne to this Son of God as the perfected Christ or Saviour is now adduced; and the two great events are made prominent which rounded the Messianic history: the Baptism with its testimony to the Son of God, and the atoning death with its testimony. Jesus came ‘by' them as the accompanying media through which He discharged His ministry and the accompanying seals which authenticated Him: these being first viewed as one, giving unity to the design of His coming into His office. St. John might have said, ‘He came in the baptism which to Him was the sealing of the Spirit, and in the atonement which finished the work to which He was sealed,' but he is using symbols, and makes the word ‘water' stand for the whole transaction at the Jordan, and ‘blood' for the whole mystery of the passion and cross. The readers of this Epistle are supposed to have the Fourth Gospel in their hands, and the doctrine of the Epistle to the Hebrews in their minds: moreover, Ephesian Christians knew well the relation of John's baptism to the baptism of Jesus (Acts 19). ‘Not in the water only, but in the water and in the blood.' The ‘by' now becomes ‘in,' to mark more impressively the essential connection between the Messiahship of Jesus and that which the water and the blood signified.
Now let us turn to the other interpretation. We mark that the two elements are separated, and each has the article: noting not merely the sacredness of the well-known symbols, but their distinction and relations. No intelligent reader could fail to think of what the writer had certainly had in his thoughts, the mysterious and miraculous effusion of blood and water when the Saviour's side was pierced. That signified, not the fact of the real humanity or real death of the Redeemer, but that the fountain was now opened for the removal of guilt by the blood, and of death by the Spirit, of the crucified; baptism and the Lord's Supper being the abiding emblems and pledges of these gifts. But St. John leaves these reflections to his readers and to us. He simply declares that Jesus came ‘not by water only,' but ‘in the water and in the blood:' not only was there one stream of life flowing from His death for us, but life under two essential aspects. Eternal life is the removal of the death of condemnation: that is symbolized by the ‘blood;' for it is the blood of Christ that cleanseth from all sin. Eternal life is also the ‘well of water springing up within the soul unto everlasting life,' of which the Saviour spoke to the Samaritan woman (John 4): in other words, it is the life of Christ Himself imparted, and of that the water is the symbol. It is usual to say that the ‘water' symbolizes the washing from sin, and the ‘blood' the sprinkling from guilt. But since the death of Christ the only washing both from sin and from guilt is by blood. The water signifies here the very well-spring of eternal life itself in Christ opened up within the soul.
The advocates of the other interpretation thus expound ‘not by water only.' John the Baptist bore witness to himself as baptizing ‘only with water,' and to Christ as ‘the Lamb of God that taketh away the sin of the world.' The Redeemer was not only authenticated in His baptism as the Son of God, the revealer of the Father and His will, but as the Lamb of God who should die for mankind: not the one without the other. He came at the Jordan that He might go on to Calvary. The apostle silently protests against those in his own day who united the Christ to Jesus in His baptism, but separated them at the cross; and He openly protests against all who limit our own baptism into Christ to mere discipleship of obedience, and forget that He is our master only because as an atonement ‘He died and revived that He might be Lord of the dead and the living.'
‘And it is the Spirit that beareth witness, because the Spirit is the truth.' Hitherto the water and the blood have not been termed witnesses: they were facts themselves witnessed by men. But the Supreme Witness of Jesus is the Holy Ghost, to whom the Saviour Himself bore witness as ‘the Spirit of the truth.' St. John singles out His testimony as the only and abiding one, with express reference to the Lord's words: ‘not we, the Baptist, the apostles, but the Spirit.' And the tense is changed: the Son of God ‘came' once in the great ministry of which water and blood were the symbols; but in the Gospels, and in the preached word, and in the sacraments, the Holy Ghost gives abiding testimony.