To this point in 1 John, the Apostle John has been instructing the Believer on the topic of prayer. Today, we come to 1 John 5:16-17 where the Apostle provides an illustration of a prayer that is in the will of God, as contrasted with one that is not in the will of God.
1 John 5:16-17 reads, "16 If you see any brother or sister commit a sin that does not lead to death, you should pray and God will give them life. I refer to those whose sin does not lead to death. There is a sin that leads to death. I am not saying that you should pray about that. 17 All wrongdoing is sin, and there is sin that does not lead to death."
The "sin that does not lead to death," is sin that does not lead to physical death. John, here, is instructing us to pray for the Believer so that God would give him the ability to choose life and God would grant him that life. The word that John uses here for "life" is Zoe. Zoe, as we have seen, includes the ability of the Believer in Christ to transcend. And when the Believer transcends, he increases in his ability to view life, including his choices, from the perspective of eternity. Part of the Believer's problem, while living in this fallen world, is this: we are limited by time. We evaluate life from the myopic view of time. The "life" that John is talking about here is the ability to evaluate time from the standpoint of eternity.
On the other hand, the death here that the Apostle is talking about is physical death. There is sin which a Christian can commit which will result in physical death. John writes, "There is a sin that leads to death. I am not saying that you should pray about that. 17 All wrongdoing is sin, and there is sin that does not lead to (physical) death." John is declaring that there are certain sins that can clearly lead to physical death. Such sins do NOT cause the Believer to lose his salvation, but these sins are physically lethal and must be shunned or the Believer is playing with death.