Matthew 12:34
You brood of vipers, how can you speak good when you are evil? For the mouth utters what the heart is full of.
Matthew 13:14-15
In their case the prophecy of Isaiah is being fulfilled: You will hear and hear but never understand, you will see and see but never perceive.
John 5:44
How can you believe, you who accept credit from one another instead of aiming at the credit which comes from the only God?
John 8:43
Why do you not understand my speech? Because you are unable to listen to what I am saying.
John 12:39-40
This was why they could not believe; for Isaiah again said,
Acts 14:16
In bygone ages he allowed all nations to go their own ways,
Romans 1:21-23
Though they knew God, they have not glorified him as God nor given thanks to him; they have turned to futile speculations till their ignorant minds grew dark.
Romans 1:28
Yes, as they disdained to acknowledge God any longer, God has given them up to a reprobate instinct, for the perpetration of what is improper,
2 Corinthians 4:3-4
Even if my gospel is veiled, it is only veiled in the case of the perishing;