Berean Standard Bible (BSB)
For although they knew God, they neither glorified Him as God nor gave thanks to Him, but they became futile in their thinking and darkened in their foolish hearts.
World English Bible (WEB)
Because, knowing God, they didn’t glorify him as God, neither gave thanks, but became vain in their reasoning, and their senseless heart was darkened.
Strong's King James
Because{G1360} that, when they knew{G1097}{(G5631)} God{G2316}, they glorified{G1392}{(G5656)} him not{G3756} as{G5613} God{G2316}, neither{G2228} were thankful{G2168}{(G5656)}; but{G235} became vain{G3154}{(G5681)} in{G1722} their{G846} imaginations{G1261}, and{G2532} their{G846} foolish{G801} heart{G2588} was darkened{G4654}{(G5681)}.
The F.O.G *
(21) Because even though they understand The אֱלֹהִים Elohim-God, they don't glorify Him as יהוה YAHWEH, or give thanks, rather they render it futile in their thoughts and their foolish hearts darkened.
The F.O.G Message *
Young's Literal Translation
because, having known God they did not glorify Him as God, nor gave thanks, but were made vain in their reasonings, and their unintelligent heart was darkened,