Romans 1:18-21

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. For since the creation of the world God's invisible qualities—his eternal power and divine nature—have been clearly seen, being understood from what has been made, so that men are without excuse.

For although they knew God, they neither glorified him as God nor gave thanks to him, but their thinking became futile and their foolish hearts were darkened.

(v18-21, NIV)

So, everybody knows the truth about God. The problem is that they suppress this truth in unrighteousness. You can't really argue and say that you never heard this truth because God has made it evident to you. You may not think that it has been made known to you because you are simply suppressing the truth. What's also interesting is that as we look to verse 21, these people did not honour God or give him thanks. God is great and worthy of praise. He and his qualities have been clearly seen. He is worthy of our honour and thanks. Yet, knowing of his eternal power and divine nature, they did not honour or thank him. So, having been made aware of God and not thanking him, they are without excuse. There is no excuse because God has made himself known.

What's interesting about God making it known is that it's like a poem. In fact, the Greek word there is where we get the word "Poem" from. If you read a poem, it implies that there was someone who wrote that poem. You wouldn't read a poem in the sand and think that the wind caused this to occur. That would only be plausible if there were someone guiding the wind as the creator of the poem. Similarly, one way God reveals himself is in the poem of his creation. There are many who look at the creation and argue for evolution and random chance. However, they are suppressors of the truth that God has made plain to them. They are without excuse.