What is the “sin unto death”?
This is a very hard question to answer because John does not give us an answer or categorize which sins lead to death in which sins do not lead to death (1 John 5:16-17). Beyond this, the general teaching of the New Testament is that all sin leads to death (Romans 6:16).
But John makes a distinction in his first epistle. He talks about sin that leads to death and sin that doesn’t lead to death. So how do we know what the difference is between these sins? First of all, Christians should not be sinning against God. He makes this argument throughout the epistle.
However, as he is talking about praying for sin, he does mention these two scenarios for Christians. This is not talking about unbelievers, but believers. This is an important distinction to make as we look at the options for what John means here.
First, let me rule out a very popular idea that John speaks of the sin that leads to death as the unpardonable sin, blasphemy of the Holy Spirit (Matthew 12:31-32; Mark 3:18-30; Luke 12:10).
The problem with this suggestion is that blasphemy of the Holy Spirit is unpardonable because it is the very last step of rejecting Christ. By the time a person commits this sin, they neither want God’s forgiveness nor are a Christian any longer. So technically, this is a sin committed by an apostate, an unbeliever.
Another possibility lies in the Jewish background of the Bible. The idea of conscious and unconscious sins comes from the Jewish background of the Old Testament law. Conscious sins are willful acts against God’s law while unconscious sins refer to sins you were not aware you committed.
I relate this to the Christian idea of sins of commission and sins of omission. Sins of commission are the six that you commit, knowing full well that you commit them at the time. These are willful sins.
The sins of omission are the ones you are not aware you have committed against God. So the idea of sins that lead to death as sins of commission and sins that do not lead to death as sins of omission could be what John is referring to.
I don’t see this kind of idea in the text of 1 John 5:16-17 either. When I don’t understand a part of the text of Scripture, I try to look around it for a context that might help me understand. Throughout the whole letter of 1 John, John has been laying out the lines between sinner and saint. I believe when he gets to this section, he wants to make distinctions for believers.
I don’t believe the language here warrants the idea that this is a person referred to as a Christian but who actually never converted to Christianity. This is not found in the New Testament. There is more evidence for apostasy, falling away from Christ, then there is for a person who is called a saint but who was never actually a Christian.
The immediate context of the book itself gives us some ideas for what may be sins that lead to death. For John, they include anything that doesn’t resemble the Christian life or being a child of God. Some of these sins he mentions throughout the book include denial that Jesus is the son of God, refusal to obey God’s commands, love of the world, and hatred of one’s brother.
I would include sins that are not repented of and confessed in the category of sin that leads to death. These are sins that Christians do not go through the proper process of confession and repentance.
First John 1:9 tells us that if we confess our sins as believers, Jesus is faithful and just to forgive us and cleanse us. If we sin against God as Christians, there is a process in place for us to restore the separation we feel. We do not lose our salvation or our relationship with God. But sin always separates, no matter who commits it.
Sins that don’t lead to death are the ones we commit that we go through the proper process of confession, repentance, and forgiveness. Though we may commit a momentary sin, going through this process restores fellowship with God, as John puts it in the beginning of 1 John (1 John 1:5-9).