Charles Spurgeon Commentary Romans 1:19-20

"because that which is known of God is manifest in them; for God manifested it unto them. For the invisible things of him since the creation of the world are clearly seen, being perceived through the things that are made, [even] his everlasting power and divinity; that they may be without excuse:" — Romans 1:19-20 (ASV)

People who have never heard the gospel can see God in His works if they open their eyes. Enough is written on the face of nature to condemn them if they do not turn to God. There is a gospel of the sea, and of the heavens, of the stars, and of the sun; and if people will not read it, they are guilty, for they are willfully ignorant of what they might know and ought to know.