If anyone sees his brother committing a sin not leading to death, he should ask God, who will give life to those who commit this kind of sin. There is a sin that leads to death; I am not saying he should ask regarding that sin.
Every sin deserves death eternally; but the elect's sins do not end in death because Christ's blood and righteousness have freed them from condemnation. You know a brother's sin is not unto death by this mark: he does not abide in it, but grieves, confesses, and forsakes it. That repentance is the sign of grace.
AI summary
We must pray for our brothers who sin, that their sins be not unto death. But there is one sin never forgiven: willful apostasy from the known truth of the gospel, the sin against the Holy Spirit. For that sin alone, prayer avails nothing.
AI summary
When a believer intercedes for his brother in sin, his prayer obtains the restoration of life that was forfeiting itself. But to "request" pardon for a sin unto death would be presumption, as though we were more merciful than God Himself. The Greek word matters: we ask humbly for a fallen brother, never demand authoritatively for the obstinate apostate.
AI summary