ISB ~ 1 John 5 v16 - 17

John distinguishes between sin that is deadly (Gk., “unto death”) and sin that is not deadly (Gk., “not unto death”). The reference is to spiritual death rather than physical death. Sinning unto death means sinning so grievously that one forfeits the indwelling “life” of Christ (5:12) and lapses back into a state of “death” (the reverse of 3:14). The evil in view is probably “apostasy”, i.e., the sin of the heretical secessionists who denied the truth of apostolic doctrine (2:22) and severed themselves from the life and liturgy of the apostolic Church (2:19). Sin that does not lead to death weakens one’s fellowship with God and requires cleansing and forgiveness (1:6-9) but does not extinguish the divine life abiding within (3:24). It is unclear why John does not ask believers to pray for persons guilty of deadly sins. Whatever the reason, his words do not imply that such a one is beyond the reach of God’s mercy or incapable of future repentance.

• Catholic moral theology adopts this distinction between mortal and non-mortal (venial) sins. Venial offenses can be forgiven by prayers of contrition and other means, but, ordinarily, mortal sins cannot be forgiven apart from the absolution and restorative grace of the Sacrament of Reconciliation (CCC 1854-64).See note on 1 Jn 1:9.