Adam Clarke on Romans 1:19

That which may be known of God - Dr. Taylor paraphrases this and the following verse thus: "Although the Gentiles had no written revelation, yet what may be known of God is every where manifest among them, God having made a clear discovery of himself to them. For his being and perfections, invisible to our bodily eyes, have been, ever since the creation of the world, evidently to be seen, if attentively considered, in the visible beauty, order, and operations observable in the constitution and parts of the universe; especially his eternal power and universal dominion and providence: so that they cannot plead ignorance in excuse of their idolatry and wickedness."