Revelation 14:7

saying with a loud voice, Fear God, and give glory to him; for the hour of his judgments is come: and worship him who made heaven, and earth, and sea, and the fountains of water.

1 Peter 2:9

but you are an elect race, a royal priesthood, a holy nation, a purchased people; that you should declare the perfections of him who has called you from darkness into his marvelous light:

Revelation 15:4

Who should not fear thee, O Lord, and glorify thy name? for thou alone art perfect. Surely all nations shall come and worship before thee, because thy righteous judgments are made manifest.

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.

Their foolish

Bible References

They glorified

Revelation 14:7
saying with a loud voice, Fear God, and give glory to him; for the hour of his judgments is come: and worship him who made heaven, and earth, and sea, and the fountains of water.
Revelation 15:4
Who should not fear thee, O Lord, and glorify thy name? for thou alone art perfect. Surely all nations shall come and worship before thee, because thy righteous judgments are made manifest.

Their foolish

1 Peter 2:9
but you are an elect race, a royal priesthood, a holy nation, a purchased people; that you should declare the perfections of him who has called you from darkness into his marvelous light: