Romans 1:21
Because, even though they in actual fact knew G-d, they did not ascribe Him kavod (glory) as G-d or give hodayah (thanksgiving) to Him, but became filled with hevel (futility, vanity, emptiness, worthlessness) in their thinking, and their senseless levavot were darkened.
Orthodox Jewish Bible
In The King James Version
In Context
22Claiming to be chachamim (wise ones), they became kesilim (fools),
Cross References
Genesis 6:5And Hashem saw that the wickedness of HaAdam was great in ha'aretz and that every yetzer (inclination) of the machshevot (thoughts) of his lev was only rah (evil) continually. + 6:5 Ro 7:18
Deuteronomy 28:29And thou shalt grope at noonday, as the ivver gropeth in darkness, and thou shalt not prosper in thy ways; and thou shalt be only oppressed and plundered evermore, and thou shalt have no moshi'a.
Psalms 50:23Whoso offereth todah glorifieth Me; 1 and to him that ordereth his derech aright 1 will I show the Salvation of Elohim.
Psalms 86:9Kol Goyim whom Thou hast made 1 shall come and worship before Thee, Adonoi; 1 and shall glorify Shimcha. 1
Isaiah 44:9They that make a pesel are all of them tohu; and their chamudim (favorite [idols]) are worthless; and they + 44:9 the idols are their own edim; they + 44:9 the idols see not, nor know; so that they + 44:9 the idol people are put to shame.
Jeremiah 2:5Thus saith Hashem: 1 What avel (wrong, fault) have avoteichem found in Me, 1 that they are strayed far from Me, 1 and have walked after hevel (vain, empty delusion), and are become deluded? 1
Matthew Henry on Romans 1:20-32
The Excellency of the Gospel. ( a. d. 58.) 19 Because that which may be known of God is manifest in them; for God hath showed it unto them. 20 For the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made, even his eternal power and Godhead; so that they are without excuse: 21 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. 22… Read the whole commentary →