“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.”
King James Version (KJV)
1:21 Because, knowing God - For the wiser heathens did know that there was one supreme God; yet from low and base considerations they conformed to the idolatry of the vulgar. They did not glorify him as God, neither were thankful - They neither thanked him for his benefits, nor glorified him for his divine perfection. But became vain - Like the idols they worshipped. In their reasonings - Various, uncertain, foolish. What a terrible instance have we of this in the writings of Lucretius! What vain reasonings, and how dark a heart, amidst so pompous professions of wisdom!
Ro 1:21 When they knew God. Had the knowledge shown in Ro 1:20. They turned from their knowledge, did not glorify the invisible Creator, yielded neither adoration nor gratitude. Became vain in their imaginations. Thoughts or reasonings. When men turn willfully from truth, they will run to the extremes of error. The world (the pagan world) yielded to idle fancies, and were involved in deeper darkness. He who shuts out the light will finally be unable to bear it. Vain. Empty, useless. See De 32:21.