They are darkened in their understanding, alienated from the life of God because of the ignorance that is in them, due to their hardness of heart.
Ephesians 4:18
A lifetime of believing and living lies imprints anti-God neural pathways that can only be rewritten with time, prayer, and dedication to the details of a new way of life.
Now this I say and testify in the Lord, that you must no longer walk as the Gentiles do, in the futility of their minds.
Ephesians 4:17
Since Paul tells the Ephesians that they must not walk as the gentiles do, he is also confirming what he said in 2:19, that they are no longer gentiles, but people of Israel.
Now this I say and testify in the Lord, that you must no longer walk as the Gentiles do, in the futility of their minds.
Ephesians 4:17
The primary mark of a true convert is a change in behavior, a discernible repentance from sin. Paul says "must", not "should". God's grace must be accompanied by obedience to his commandments, not because obedience is the price of grace, but because obedience is the only appropriate response to grace.