The “sin unto death is, in context, a sin committed by a Christian “brother,” not an unbeliever, and so is not the so-called “unforgivable sin,” the blasphemy against the Holy Spirit. Christ said the latter sin cannot be forgiven, “neither in this world, neither in the world to come” (Matthew 12:32). It is the ministry of the Holy Spirit to convict unbelievers “of sin, because they believe not on me” (John 16:8-9). If a person irrevocably rejects Christ, even after he fully understands the evidences of His deity, His substitutionary death with its offer of salvation, and the awful consequences of eternity without Him, then he “hath done despite to the Spirit of grace” (Hebrews 10:29). In effect, he has put his faith in Satan rather than Christ, and there is nothing more that Gods Holy Spirit canor willdo. This is the truly unforgivable sin.
The Christian can persist in some known sin, though not the sin of total unbelief or willful apostasy; a true Christian will not commit that kind of sin. If he deliberately continues to practice ungodliness in life or doctrine, however, refusing to repent, not even responding to Gods chastening discipline (note Hebrews 12:5-11), then the only recourse of the Lord may be to send physical death, although not eternal spiritual death, for such a person is delivered “to Satan for the destruction of the flesh, that the spirit may be saved in the day of the Lord Jesus” (1 Corinthians 5:5).
This is a fearful prospect even for the believer, and should be a sober warning against persistence in any known sin. “He shall suffer loss: but he himself shall be saved; yet so as by fire” (1 Corinthians 3:15).
The verse reads, “If any man see his brother sin a sin which not unto death, he shall ask, and He shall give him life.” (1 John 5:16). This situation in Corinth illustrates this principle. God chastened some believers who sinned in Corinth with a sickness that led to their physical death (1 Corinthians 11:30). This may also be the “like measure” taken in James 5:14, 15. In cases where chastisement results in physical death, prayer will not succeed in turning away the divine rod of chastening. These believers, as was true of Ananias and Sapphira, do not lose the salvation of their souls, but their physical life on earth is ended. But if the sin is not “unto death” as Gods form of chastisement, we can pray for the fellow believer and God will restore him.
The “sin unto death” is not a single, isolated act, but one that has been repeated over and over again by the disobedient child of God. The words “If a man see.” seem to indicate that the sinning involved some overt action, probably something that affected the entire assembly of believers.
The Scriptures teach there is no sin that God cannot forgive. “Whoever believes in [Jesus Christ] should not perish, but have eternal life” (John 3:16).
Even as Christians we may sin against God. When we do, God disciplines us, as a father disciplines his erring children. “Those whom the Lord loves He disciplines” (Heb. 12:6).
God may discipline us through physical sickness, although not all sickness is the result of specific sin. God may also give us mental frustration or a lack of inner peace. As a last resort, God may remove us by physical death. This happened to some in Corinth who misused the Lords Supper (I Cor. 11:30; cf. John 15:2).
The apostle points out in 1 John 5:16 that believers can sin to the point that Gods judgment is physical death. The Greek shows he is talking about sin, though not a specific sin. This should remind us to respond immediately when God disciplines us.
In my judgment, 1 John 5:16 echoes Jeremiah 11, and similar texts in that book. Israel had returned to the sins of their forefathers and, God says, “refused to listen to my words.” The people were joined to their idols. According to 2 Chronicles 36:16, “They mocked Gods messengers, despised his words, and scoffed at his prophets. until there was no remedy.” So the Lord says to Jeremiah, “Do not pray for this people because I will not listen when they call to me in the time of their distress.” The sin unto death is determined, open rebellion against God by a person who once professed to know and love Him.
John says that we need not pray for such a person. There is no remedy.