One eternal sin, known as blasphemy against the Holy Spirit or the sin unto death, is explicitly mentioned in various passages of the Synoptic Gospels (Mark 3:28–29, Matthew 12:31–32, and Luke 12:10) as well as in other New Testament references (Hebrews 6:4–6, Hebrews 10:26–31, and 1 John 5:16).
