Romans 1:18-19

The wrath of God is being revealed from heaven against all the godlessness and wickedness of men who suppress the truth by their wickedness, since what may be known about God is plain to them, because God has made it plain to them.

(v18-19, NIV)

There's this truth about God that people know. Unfortunately, people suppress this truth in unrighteousness. Now some may object saying that some do not know this truth. If someone never heard or knew of this truth, it wouldn't be their fault, would it? Unfortunately, that's not a valid excuse. The truth is evident to them. You can argue all you want that you never knew it, but you refuse to admit that you knew it because you suppress the truth. The truth is evident to you; you have no excuse. You can argue all you want with others or with God, but it is evident to you. In fact, God has made it evident to them. God is the one who makes plain the truth about himself. He reveals the truth about himself to all. He makes it plain, so they are without excuse. You have no excuse, you who suppress the truth, because the truth was made evident to you by God.