The apostle John writes to at least one congregation burdened with controversy. Separatists claiming to be perfect and sinless in some fashion gave way to every kind of sin, believing it to be of no consequence. Worse still, they could not leave well enough alone, but continually assaulted their former brothers with accusations that they alone knew the real “truth.” Had not Jesus forgiven all sins? Why not, then, sin all the more, because self-effort meant nothing? Salvation comes by grace, after all, and not by works.
John, unlike these separatists, did not engage in direct polemics. “They went out from us, but they were not of us; for if they had been of us, they would have continued with us. But they went out, that it might become plain that they all are not of us” (1 John 2:19). Thus, John writes to the beleaguered congregations, who were anxious and likely wondering whether what their former brethren said was true. There is no reason to fear, even though the spirit of Antichrist goes out into the world in these men, because God has not left His people without reassurance.
John emphasizes that one such proof of being in the Lord and not in the world is whether a man keeps the commandments of God. While John, in his often repetitious fashion, highlights this point throughout the letter, he states this clearly immediately prior to the reading: “For this is the love of God, that we keep His commandments” (1 John 5:3). This is not a reversal of the Biblical order. Good works do not produce faith, but good works are certainly the evidence of such faith, and a willful refusal to seek to keep the commandments of God is a clear sign of a lack of faith. John even goes as far as to say that “I am writing these things to you so that you may not sin” (1 John 2:1). The one who is in Christ no longer “does sin,” to use a more literal translation of phrases like “make a practice of sinning.” The Christian does not aim for fewer sins than yesterday; the Christian is called to aim for no sins whatsoever. It is this desire for an actual sinlessness, even in the midst of sin and death, that distinguishes a Christian from the world.
Yet John also points to another comfort for these troubled Christians: faith. The one who believes in Jesus has a real victory over the world and over the desire to sin. At this point, John seems to address other objections from the separatists, who may have argued that Jesus was not actually God (such as in 1 John 2:22 or 1 John 4:3) or that He was not actually a man (which explains his emphasis on Jesus coming “in the flesh” in 1 John 4:2). There may have been two separate groups, for that matter. But his point is clear: God Himself bears witness regarding His Son, and this testimony is greater than the testimony of men, orthodox or otherwise.
There is a real temptation to understand “water and blood” in 1 John 5:6 as referring to the Sacraments, but this needs to be resisted for a number of reasons. First of all, “he who came” is clearly in the past tense, referring to previous events. Christ does indeed come, as He promised, in the Sacraments, but the wording here looks backwards. Second, “blood” all by itself would be an odd way to refer to the Lord’s Supper, considering that even Paul in 1 Corinthians 11:26 refers to the two elements of that Sacrament separately. Third, John’s emphasis that Christ did not come “by the water only” suggests that some had argued this way, and therefore not “by blood,” which could be a denial that He had come in the flesh.
Therefore, “water” here seems to be a reference to Christ’s own Baptism rather than Christian Baptism generally (Matthew 3:13-17; Mark 1:9-11; Luke 3:21-22). Additionally, each of the passages cited include a clear reference to the Lord’s own testimony, quoting Psalm 2:7 regarding Jesus. At the beginning of Jesus’ public ministry, therefore, the Father Himself bears testimony with the Spirit regarding Christ. “Blood,” therefore, seems to refer to Christ’s death on the cross, when He shed His blood for the forgiveness of sins. Taken together in this way, water and blood refer to the whole work of Christ, Immanuel in the flesh. It was John, after all, who wrote concerning the purpose of his Gospel that “these [things] are written so that you may believe that Jesus is the Christ, the Son of God, and that by believing you may have life in his name” (John 20:31).
The Holy Spirit also bears witness to the truth, because He is the Spirit of Truth (John 15:26). As John emphasizes in his Gospel, the Holy Spirit dwells within those who are of God and bears testimony through His living voice about Jesus (John 14:17). His testimony does not conflict with the testimony of the water and blood, because it is that very testimony that He has been sent to proclaim. Speaking through His holy Word, the Scriptures, the Holy Spirit works faith according to His purposes and causes that faith to bear the fruit of good works. This, then, is why faith and good works ultimately go together, because both flow from God.