"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." - Romans 1:21
This indictment is about what we do with what we know. It is an offense to reason not to be thankful to God and glorify God as God. Thanksgiving is a national holiday because even non-believers have enough understanding to know that they did not create all the blessings of this world.
There will always be more left unknown than grasped with our mortal minds. We do not know all there is to know about God. We don't know a fraction. What we do know is enough to call us to worship.
People have known God through the centuries. They have known enough to treat Him like God. How is that? Worshipfully, doing what we call "glorifying."
To glorify is to recognize the extreme weightiness of a matter. In this case, it is to take God so seriously that we stand in awe, are struck down by the sheer magnitude of God’s power and are overwhelmed with the right kind of fear as we behold the divine majesty.
The right kind of reverence is the stuff that makes our jaws drop, that leaves us speechless, that causes us to tremble, that turns on the lights and lets us know that if we get this part right, we don't really have to worry about anything else.
Paul says folks who knew God failed to be
What does God want?
God wants us to take Divinity seriously.
God wants us to experience and glorify the One who is Holy with gratitude.
Only when we take God seriously, can we take ourselves seriously - or anything else for that matter.
Paul says that without the cornerstone of acknowledgement of God as God, man became and we become futile thinkers, vain imaginers. Thanksgiving is a good time to renew this important missing element of worship in our lives.