“The Witness of God”
This is he who came by water and blood—Jesus Christ; not by the water only but by the water and the blood. And the Spirit is the one who testifies, because the Spirit is the truth. For there are three that testify: the Spirit and the water and the blood; and these three agree. If we receive the testimony of men, the testimony of God is greater, for this is the testimony of God that he has borne concerning his Son. Whoever believes in the Son of God has the testimony in himself. Whoever does not believe God has made him a liar, because he has not believed in the testimony that God has borne concerning his Son. And this is the testimony, that God gave us eternal life, and this life is in his Son."
1 John 5:6-11
The first letter of John was written to encourage and protect Christians from the error of false teachers, further establishing them in their faith. In this short letter, which reads more like a sermon, John explains his purpose for writing in three statements: to complete Christian joy (1 Jn. 1:4), to encourage holy living (1 Jn. 2:1), and to provide believers with assurance of their salvation (1 Jn. 5:13). Whereas John's gospel was written to produce faith in Christ "and that by believing [they] may have life in his name" (Jn. 20:31), John's letter was written to encourage those who already believe that they "may know that [they] have eternal life" (1 Jn. 5:13).
Throughout the book, John weaves together three tests by which Christians can confirm their standing with God against the counterfeit assurance of unbelievers: the doctrinal test of believing in Jesus as the Christ, the Son of God (1 Jn. 3:23; 5:5, 10, 13); the moral test of keeping God's commands (1 Jn. 1:5; 3:5, 9); and the social test of loving other Christians (1 Jn. 4:7-11).
It is difficult to know the identity of the false teachers but John describes them as "false prophets" (1 Jn. 4:1-6), "deceivers" (2 Jn. 7) and "antichrists" (1 Jn. 2:18, 22). At one time, they passed as true Christians but had since seceded from the Christian community (1 Jn. 2:19) and "gone out into the world" (1 Jn. 4:1; cf. 2 Jn. 7) to spread their lies about Jesus. They denied the fleshly incarnation of Jesus (1 Jn. 4:2; 2 Jn. 7) and their theological error resulted in making outrageous claims about sin that led to moral degradation (1 Jn. 1:6-10; 2:29-3:10).
After teaching that we can overcome the world through our faith in Jesus as "the Son of God" (1 Jn. 5:5), John confirms Jesus' identity by bearing witness to it (1 Jn. 5:6-11). He presents three "external" witnesses that all agree (Spirit, water, blood, v.8) along with two "internal" witnesses that agree (faith, v.10, and eternal life, v.11). The reason for presenting all this evidence is to confirm for the believer that their faith in Christ is not in vain and that through that faith they overcome the world (1 Jn. 5:5).
According to the Law of Moses, evidence was confirmed based upon the testimony of "two or three witnesses" (Deut. 19:15). These, God has provided concerning his Son. The "water" refers to Jesus' baptism whereby both the Father and the Spirit testified to his identity as God's Son (Mt. 3:16-17), and the "blood" refers to Jesus' sacrificial death on the cross, witnessed by the Spirit in the Old Testament (see Isaiah 53). The "Spirit" also bore witness to Jesus' identity as God's Son at his baptism (Jn. 1:32), during his ministry as he performed miracles (Heb. 2:3-4), and after his ascension through the apostles (Acts 1:8). The Spirit continues to testify to Jesus' identity in the Scriptures (2 Pet. 1:19-21).
These three witnesses all agree and tell the truth about Jesus. This is God's testimony concerning his Son. If we believe our fellow man in a court of law based on the testimony of two or three witnesses, how much more ought we to believe God? (1 Jn. 5:9) To those who accept God's testimony he gives "eternal life" in his Son (1 Jn. 5:11). Those who reject God's testimony accuse him of lying (1 Jn. 5:10; 1:10). In forfeiting the Son, they forfeit eternal life (1 Jn. 5:12).
An important textual note regarding 1 John 5:7-8 must be made. The King James Version, which bases its translation on the Textus Receptus, includes what textual critics call the Comma Johanneum:
"in heaven, the Father, the Word, and the Holy Spirit, and these three are one. And there are three that testify on earth"
The evidence, both internal or external, is against its authenticity. Externally, this longer reading is found only in ten very late manuscripts (mss), four of which have the words in a marginal note. These mss range in date from the 10th century to the 18th. It was inserted into the Latin translation of the Bible, the Vulgate, probably to affirm in one convenient place the trinitarian view of God. Internally, the context of John shows that this was a later addition: John is talking about the witness in regards to Jesus as God's Son. The truth of God as one in three persons can be well established elsewhere in the Bible without this spurious addition to Scripture.