Chapter 5:16-17 (ESV) - 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.
Question to consider: What is the distinction between a sin that does and does not lead to death?
I think we should be careful about building entire doctrines around a couple of verses unless we know that the doctrine is clearly representing the intent of the author. Throughout this commentary, John has contrasted those in the faith who worshiped a Christ who came in the flesh and physically paid for our sins on the cross with those who denied Christ, cursed the body of believers and walked away from the faith. Those in the faith had the assurance of eternal life whereas those who abandoned the faith could only expect death and judgment.
So when John speaks of mortal and venial sins like he does in these verses, I think it’s important that we understand them in this context. “Death” here is a reference to the second death, eternal separation from God. If we look at this way, John is making a similar point to James at the end of his epistle, “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)
If someone is being deceived in such a way that they are ready to abandon the faith, we are not to just sit back and pray for their return but to go after them and do everything we can to keep them from this path that leads to death. For our daily struggles with sin and temptation, we pray for deliverance. For our struggles with one another, we forgive and receive forgiveness. Jesus told us to pray, “...And forgive us our debts, as we also have forgiven our debtors. And lead us not into temptation, but deliver us from evil.” (Matthew 6:12-13)
We should also be reminded here that while we draw breath, God will continue to extend mercy to those who repent and return to Him. Remember from the beginning of this writing, “If we confess our sins, he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness.” (1 John 1:9) Confessing our sins, repenting of them, and producing fruit in keeping with repentance helps to keep sin from darkening our hearts to the point where we walk away from the faith.
Martin Luther affirmed this need for continual confession and absolution. The objection which was nailed to the door at the church in Whittenberg was about the doctrine of penance. Penance is a set of actions prescribed by a priest to bring about the necessary sorrow and contrition someone needs in order to receive absolution.
Luther argued that upon confession of sin, the finished work of Christ on the cross demands our immediate pardon. Our forgiveness is a gift of mercy, and any works required of us to receive it is an affront to the work of Christ in granting us this gift. If someone gives you a gift, the appropriate response is to receive it with gratitude and not to attempt to repay it.
Dear heavenly father, thank You for granting us grace and forgiveness through Jesus. May we receive this gift freely with gratitude and just as freely grant it to others. Please keep us from deceit and temptation and help us to remain firm in the faith. Give us the courage to go after those who are going down the path of sin that leads to death. Amen.