Ephesians 4:18

in the vanity of their mind, darkened in their understanding, and alienated from the life of God, through the ignorance that is in them, by reason of the hardness of their heart:

Ephesians 2:12

and ye were at that time without Christ, aliens from the commonwealth of Israel, and strangers to the covenants of promise, having no hope, and without God in the world: but now in Christ Jesus,

Galatians 4:8

But then indeed, when ye knew not God, ye served those which in reality are no gods.

1 Thessalonians 4:5

not in the passion of lust, like the heathens who know not God.

Acts 17:30

Wherefore though God overlooked the times of this ignorance, He now requireth all men every where to repent.

Romans 1:21-23

so that they are inexcusable; because having thus known God they glorified Him not as God, neither were they thankful; but were infatuated by their own reasonings, and their heart being void of understanding was darkened.

Romans 11:25

For I would not have you, brethren, to be ignorant of this mystery, (least ye should be wise in your own eyes) that blindness in part is befallen Israel, till the fulness of the Gentiles be come in.

Matthew 13:15

and their ears are dull of hearing, and they have closed their eyes; least they should see at all with their eyes, and hear with their ears, and understand with their heart, and be converted, and I should heal them.

Mark 3:5

And when He had looked round upon them with indignation, being grieved at the hardness of their hearts, He saith to the man, Stretch out thine hand: and he stretched it out, and his hand was made as sound as the other.

John 12:40

He hath blinded their eyes, and hardened their heart, that they might not see with their eyes, and understand with their heart, and be converted, and I should heal them.

Acts 26:17-18

delivering thee from the people and from the Gentiles, to whom I now send thee,

Romans 1:28

And as they were not careful to acknowledge God, God gave them up to an undiscerning mind to do things that were not fit to be done:

Romans 2:19

and art persuaded that thou art a guide of the blind,

Romans 8:7-8

because the carnal mind is an enemy to God; for it is not subject to the law of God, nor indeed can be:

1 Corinthians 1:21

For, since in the wisdom of God the world by it's wisdom knew not God, it pleased God by what they called the folly of preaching to save those that believe.

2 Corinthians 3:14

for unto this day the same veil remaineth unremoved in the reading of the old testament, which veil is taken away in Christ.

2 Corinthians 4:4

among whom the god of this world hath blinded the minds of the unbelieving, so that the light of the glorious gospel of Christ, who is the image of God, doth not shine unto them:

Colossians 1:21

And you that were formerly alienated, and enemies in your mind by wicked works,

James 4:4

Ye adulterers and adulteresses, know ye not that the friendship of the world is enmity to God? whosoever therefore will be a friend of the world becomes an enemy of God.

1 John 2:11

But he, that hateth his brother, is in darkness, and walketh in darkness, and knoweth not where he goeth, because the darkness hath blinded his eyes.

Treasury of Scripture Knowledge

Summary

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:

Bible References

The understanding

Acts 17:30
Wherefore though God overlooked the times of this ignorance, He now requireth all men every where to repent.
Acts 26:17
delivering thee from the people and from the Gentiles, to whom I now send thee,
Romans 1:21
so that they are inexcusable; because having thus known God they glorified Him not as God, neither were they thankful; but were infatuated by their own reasonings, and their heart being void of understanding was darkened.
1 Corinthians 1:21
For, since in the wisdom of God the world by it's wisdom knew not God, it pleased God by what they called the folly of preaching to save those that believe.
2 Corinthians 4:4
among whom the god of this world hath blinded the minds of the unbelieving, so that the light of the glorious gospel of Christ, who is the image of God, doth not shine unto them:
Galatians 4:8
But then indeed, when ye knew not God, ye served those which in reality are no gods.
1 Thessalonians 4:5
not in the passion of lust, like the heathens who know not God.

Alienated

Ephesians 2:12
and ye were at that time without Christ, aliens from the commonwealth of Israel, and strangers to the covenants of promise, having no hope, and without God in the world: but now in Christ Jesus,
Romans 8:7
because the carnal mind is an enemy to God; for it is not subject to the law of God, nor indeed can be:
Galatians 4:8
But then indeed, when ye knew not God, ye served those which in reality are no gods.
Colossians 1:21
And you that were formerly alienated, and enemies in your mind by wicked works,
1 Thessalonians 4:5
not in the passion of lust, like the heathens who know not God.
James 4:4
Ye adulterers and adulteresses, know ye not that the friendship of the world is enmity to God? whosoever therefore will be a friend of the world becomes an enemy of God.

Because

Romans 1:21
so that they are inexcusable; because having thus known God they glorified Him not as God, neither were they thankful; but were infatuated by their own reasonings, and their heart being void of understanding was darkened.
Romans 2:19
and art persuaded that thou art a guide of the blind,
1 John 2:11
But he, that hateth his brother, is in darkness, and walketh in darkness, and knoweth not where he goeth, because the darkness hath blinded his eyes.