As Tom Wright observes, natural theology has attached itself to Romans 1:19-21 and gotten all it can out of these verses.
For what can be known about God is plain to them, because God has shown it to them. 20 Ever since the creation of the world his eternal power and divine nature, invisible though they are, have been understood and seen through the things he has made. So they are without excuse; 21 for though they knew God, they did not honor him as God or give thanks to him, but they became futile in their thinking, and their senseless minds were darkened.
What Wright also observes is that saving knowledge does not come through natural theology. Eikons are made in such a way that they can see through creation and see God: Creation, Paul is saying, is eikonic at some level. Creation is designed to lead the observer from what is seen to what is not seen. Creation witnesses to the glory of God.
The tragedy of the suppressors is that instead of a “seeing-through” creation there is a “staring-at”creation that becomes idolatrous. Instead of seeing through creation, they see creation and stop right here.
There are all sorts of stop-outs and cut-offs in our world: nature mysticism, romanticism of certain sorts, materialism, house-worship, beauty-worship, science-is-all-we know type things, etc. You may think of some others.
At any rate, we would do well today to pause and look at creation and see through creation, to see that it is designed to lead us through its beauty to God and it really does want to prevent us from doing what is so often done: stopping right there and dwelling on nature instead of the creator.