Ephesians 4:19

Understanding darkened. The idea is that of blindness of the intellect. The metaphor of darkness is used frequently in Scripture (John 3:19; Acts 26:18; Col. 1:13; 1 Thess. 5:4, 5; 1 John 1:5, 6). The natural mind cannot comprehend spiritual truth, for it has been corrupted by sin, not only in its moral perceptions but in its reasoning capacities. Unaided reason is wholly unequal to the spiritual insights necessary to a saving acquaintance with God.

Alienated. See on Eph. 2:12; cf. Col. 1:21. This word, and the Greek one from which it is translated, suggest a former condition of union. Man, who once held communion with his Maker, is now separated from the life of God, that is, from the life that comes from Him (1 John 5:11). Alienation from the life of God means the loss of eternal life — spiritual death.

Ignorance. Their ignorance resulted, not from an intellectual incapacity, but from a moral lack for which they could be held responsible. Ignorance of the will of God is no excuse when one has had the opportunity to know that will, for God can never “wink” at a guilty ignorance (cf. Acts 17:30).

Blindness. Gr. porosis, “hardening,” the idea being that of spiritual callousness and insensibility (cf. Rom. 11:25). In Rom. 1:21 Paul describes how this hardening came about, the implication there as well as here being that men have brought it on themselves.