If anyone sees his brother committing a sin not leading to death, he shall ask, and God will give him life—to those who commit sins that do not lead to death. There is sin that leads to death; I do not say that one should pray for that. All wrongdoing is sin, but there is sin that does not lead to death. – 1 John 5:16-17 ESV
John has just finished encouraging his readers “that if we ask anything according to his will he hears us” (1 John 5:14 ESV). Now he provides a practical example of that kind of prayer. It is a scenario that each and every one of us has experienced at one time or another in our lives as believers. We have all found ourselves at one time or another in the unpleasant position of having seen a fellow brother or sister in Christ committing a sin of some kind. It could be that we caught them in a lie or we discovered a moral indiscretion. John's seems to be referring to a sin that is visible, not hidden. And his point is that the sin that is seen is one being committed by a believer. When that happens, we are to pray. We are to take the matter to God. This does not necessarily mean that we are not to confront the one we have witnessed committing the sin. James makes it clear that we have an obligation to help turn a brother from his son. “My brothers, if anyone among you wanders from the truth and someone brings him back, let him know that whoever brings back a sinner from his wandering will save his soul from death and will cover a multitude of sins” (James 5:19-20 ESV). We are to do all that we can to help bring back a sinner from his wandering. But John's counsel is to begin with prayer. We are to take the matter to God. This is wise advice, because, ultimately, repentance is the work of the Spirit of God. We can confront, but God must convict. We can expose the sin, but only God can expose and expunge the sin from the heart of the sinner. So we must begin with prayer. We must pray for wisdom, so that what we say is communicated in love and in truth. We must pray for the Spirit to prepare the heart of the one who has sinned, so that they might be receptive to our words. We must ask God to bring about conviction and a heart of repentance. John indicates that our prayer will give the one for whom we pray life. Ultimately, it is God who gives life. We must always understand that our words accomplish nothing. It is God alone who can bring back a sinner from his sin. But God may use us in the process. We must remember that God has placed us in the body of Christ for a reason. We are to care for and love one another. At times that takes the form of admonishment and requires loving confrontation, but it must always be done wisely and under the direction of the Holy Spirit.
In this passage John speaks of two kinds of sin. He encourages us to pray for a brother or sister in Christ who has committed a sin that does not lead to death. But he also refers to a sin that does lead to death. What is he talking about? What is this sin that leads to death? I think the key to understanding this passage is to remember the context. This entire letter began with the encouragement to remember that Jesus was the Christ, the Son of God. John has spent the entire letter giving proof as to the deity of Jesus and providing evidence of His claim to be the Savior of the world. For John, the rejection of Jesus as Savior is the sin that leads to death. That is why he makes it clear that our prayer is to be for a fellow believer. And our prayer is to be for any and all sins a believer in Jesus Christ might commit. But it does not include the sin of rejecting Christ as Savior, because the one for whom we are praying is a believer. For anyone who refuses to accept Jesus Christ as the Son of God and their sin-substitute, the consequences are deadly. To deny Jesus as Savior is to remain dead in your trespasses and sins and under God's sentence of eternal separation from Him. “The distinction between the two sins must be found in the fact that sin ‘unto death’ is the Christ-rejecting behavior evidenced by those who also deny their own sinfulness, their need for atonement, and Christ’s ability to provide that atonement. Their sin is deadly because in the context of their current fundamental attitude towards Christ they have no hope of atonement’” (Tim Ward, ‘Sin “Not unto Death” and Sin “Unto Death” in 1 John 5:16’, Churchman 109 (1995), 236). This is not to say that we should refuse to pray for the lost. That is not John's point. His emphasis in this passage is to call believers to take sin seriously and pray for one another. He is providing a clear example of what it means to love one another. We love one another the most when we desire for one another God's best. Sin should be unacceptable to us – whether in our own life or in the life of a fellow believer. We should love one another enough to risk offense for the sake of our brother's spiritual condition. Love for our brother should outweigh fear of rejection. Their holiness should mean far more to us than their temporary happiness. Paul would have us remember, “For the kind of sorrow God wants us to experience leads us away from sin and results in salvation. There's no regret for that kind of sorrow. But worldly sorrow, which lacks repentance, results in spiritual death” (2 Corinthians 7:10 NLT). So don't be afraid to speak up. But before you do, make sure you lift up the matter to God.