Having the understanding darkened, being alienated from the life of God through the ignorance that is in them, because of the blindness of their heart:
Berean Study Bible (BSB) - Ephesians 4:18 >They are darkened in their understanding and alienated from the life of God because of the ignorance that is in them due to the hardness of their hearts.
Textus Receptus (TR) - Ephesians 4:18 >ἐσκοτισμένοι τῇ διανοίᾳ, ὄντες ἀπηλλοτριωμένοι τῆς ζωῆς τοῦ Θεοῦ διὰ τὴν ἄγνοιαν τὴν οὖσαν ἐν αὐτοῖς, διὰ τὴν πώρωσιν τῆς καρδίας αὐτῶν·