A.T. Robertson Commentary Ephesians 4:18

"being darkened in their understanding, alienated from the life of God, because of the ignorance that is in them, because of the hardening of their heart;" — Ephesians 4:18 (ASV)

Being darkened (εσκοτωμενο οντες). Periphrastic perfect passive participle of σκοτοω, old verb from σκοτος (darkness), in N.T. only here and Re 9:2; 16:10.

In their understanding (τη διανοια). Locative case. Probably διανοια (δια, νους) includes the emotions as well as the intellect (νους). It is possible to take οντες with απηλλοτριωμενο which would then be periphrastic (instead of εσκοτωμενο) perfect passive participle.

From the life of God (της ζωης του θεου). Ablative case ζωης after απηλλοτριωμενο (2:12).

Because of the ignorance (δια την αγνοιαν). Old word from αγνοεω, not to know. Rare in N.T. See Ac 3:17.

Hardening (πωρωσιν). Late medical term (Hippocrates) for callous hardening. Only other N.T. examples are Mr 3:5; Romans 11:25.