Unthankfulness

"One of the marks of someone who does not know God, is unthankfulness."

because, although they knew God, they did not glorify Him as God, NOR WERE THANKFUL, but became futile in their thoughts, and their foolish hearts were darkened.
Romans 1:21 NKJV

But know this, that in the last days perilous times will come: For men will be lovers of themselves, lovers of money, boasters, proud, blasphemers, disobedient to parents, UNTHANKFUL, unholy,
II Timothy 3:1‭-‬2 NKJV

Do all things WITHOUT COMPLAINING and disputing, that you may become blameless and harmless, children of God without fault in the midst of a crooked and perverse generation, among whom you shine as lights in the world,
Philippians 2:14‭-‬15 NKJV

Rejoice always, pray without ceasing, IN EVERYTHING GIVE THANKS; for this is the will of God in Christ Jesus for you.
I Thessalonians 5:16‭-‬18 NKJV