Was the man in 1 Corinthians 5 committing a sin unto death?
The man in 1 Corinthians 5 was committing a sin unto death, a sin gross enough that God would take the believer out ahead of time if he did not repent and turn from living with his stepmother in a marital relationship. Scripture calls it deliverance to Satan for the destruction of the flesh so the spirit may be saved.
Les explains that all unrighteousness is sin, whether little or great, and there is a sin not unto death, implying some sin is gross enough that God will take that believer out ahead of time. He then points to 1 Corinthians 5, where the man is evidently committing a sin unto death. It is worthy of death if he does not repent and turn around. If he continues living with his stepmother in a marital relationship, God will take him out of Corinth. The instruction is to deliver such a one unto Satan for the destruction of the flesh, that the spirit, the soul, may be saved in the day of the Lord Jesus. Les also notes the congregation was glorying and puffed up, not recognizing that a little leaven leaveneth the whole lump. He applies this to the church today, which has accommodated social sins rather than dealing with them.