Mark 4:12
That seeing they may see, yet not perceive; and hearing may hear, yet not understand; lest at any time they should be converted, and their sins be forgiven them.
Mark 8:17-21
And Jesus knowing it said unto them, Why reason ye together, because ye have no loaves? Do ye not yet consider, nor understand? Have ye your heart yet hardened?
Ephesians 2:11
Wherefore remember that ye in time past were Gentiles in the flesh, who are called uncircumcision by that called circumcision made by hands in the flesh;
2 Thessalonians 2:10-12
and in every unrighteous delusion among those who perish: in consequence of which things they received not the love of the truth, that they might be saved.