Romans 1:21

for although they knew God they did not honor him as God or give thanks to him, but they became futile in their thinking, and their foolish hearts were darkened.

Ephesians 4:17-18

Now this I affirm and testify in the Lord, that you must no longer live as the Gentiles do, in the futility of their minds,

Romans 1:19

for what may be known about God is plain to them, because God has shown it to them.

Revelation 14:7

and he said with a loud voice, "Fear God, and give him glory, because the hour of his judgment has come; worship him who made the heaven and the earth and sea and springs of water."

Luke 17:15-18

Then one of them, when he saw that he was healed, turned back, praising God with a loud voice;

John 3:19

And this is the judgment, that the light has come into the world, and men loved darkness rather than light, because their deeds were evil.

Romans 1:28

And since they did not see fit to retain the knowledge of God, God gave them over to a base mind, to do what ought not to be done.

Romans 11:10

Let their eyes be darkened so that they cannot see, and bend their backs forever."

Romans 15:9

and in order that the Gentiles might glorify God for his mercy. As it is written: "Therefore I will praise you among the Gentiles, and sing to your name";

2 Timothy 3:2

For men will be lovers of self, lovers of money, boastful, arrogant, abusive, disobedient to their parents, ungrateful, unholy,

1 Peter 1:18

You know that you were redeemed from the futile way of life inherited from your forefathers, not with perishable things such as silver or gold,

1 Peter 2:9

But you are a chosen race, a royal priesthood, a holy nation, a people for God's own possession, that you may declare the praises of him who called you out of darkness into his marvelous light.

Revelation 15:4

Who will not fear, O Lord, and glorify your name? For you alone are holy. All the nations will come and worship before you, for your righteous acts have been revealed."

Acts 26:18

to open their eyes, so that they may turn from darkness to light and from the power of Satan to God, that they may receive forgiveness of sins and a place among those who are sanctified by faith in me.'

Treasury of Scripture Knowledge

Summary

Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened.

General references

Bible References

When

Romans 1:19
for what may be known about God is plain to them, because God has shown it to them.
John 3:19
And this is the judgment, that the light has come into the world, and men loved darkness rather than light, because their deeds were evil.

They glorified

Romans 15:9
and in order that the Gentiles might glorify God for his mercy. As it is written: "Therefore I will praise you among the Gentiles, and sing to your name";
Luke 17:15
Then one of them, when he saw that he was healed, turned back, praising God with a loud voice;
2 Timothy 3:2
For men will be lovers of self, lovers of money, boastful, arrogant, abusive, disobedient to their parents, ungrateful, unholy,
Revelation 14:7
and he said with a loud voice, "Fear God, and give him glory, because the hour of his judgment has come; worship him who made the heaven and the earth and sea and springs of water."
Revelation 15:4
Who will not fear, O Lord, and glorify your name? For you alone are holy. All the nations will come and worship before you, for your righteous acts have been revealed."

But became

Ephesians 4:17
Now this I affirm and testify in the Lord, that you must no longer live as the Gentiles do, in the futility of their minds,
1 Peter 1:18
You know that you were redeemed from the futile way of life inherited from your forefathers, not with perishable things such as silver or gold,

Their foolish

Romans 11:10
Let their eyes be darkened so that they cannot see, and bend their backs forever."
Acts 26:18
to open their eyes, so that they may turn from darkness to light and from the power of Satan to God, that they may receive forgiveness of sins and a place among those who are sanctified by faith in me.'
1 Peter 2:9
But you are a chosen race, a royal priesthood, a holy nation, a people for God's own possession, that you may declare the praises of him who called you out of darkness into his marvelous light.

General references

James 4:17
Therefore, to one who knows the right thing to do and does not do it, to him it is sin.