Romans 3:11
No one understands [everything]. No one looks to God [all the time].
Matthew 13:13-14
Therefore, I am speaking to them with parables because [although] they can see, they [really] do not perceive, and [although] they can hear, they [really] do not comprehend, and so they [utterly] fail to understand [what I am trying to get across].
Matthew 13:19
When anyone hears the message of the kingdom but does not understand it, the evil one [i.e., the devil] comes to him and grabs away what had been sown in his heart. This is the person who was scattered to the side of the road.
Romans 1:22
They claimed to be wise, but became fools,
Romans 1:28
And since these people refused to acknowledge God, He has allowed [or, abandoned] them to have degraded minds and to practice those things which they should not do.
Romans 8:7
This is because the one whose mind is [controlled] by the flesh is an enemy of God; for he is not obedient to God's law, and in fact, cannot obey it.
Titus 3:3
For we [Christians] were also once foolish, disobedient, deceived, enslaved to various kinds of [evil] desires and [sinful] pleasures. [We used to] live in malice and envy, hating people and being hated by them.
1 John 5:20
And [in addition], we know that the Son of God has come [in a physical body, See 4:2] and has given us understanding, so that we can know the True One [i.e., God], and that we are in [fellowship with] the True One, even His Son Jesus Christ. This Son is the true God and eternal life.