Because that which may be known of God is manifest in them; for God has showed it unto them.
All Commentaries on Romans 1:19 Go To Romans 1
Ambrosiaster
AD 400
The knowledge of God is plain from the structure of the world. For God, who by nature is invisible, may be known even from things which are visible. For his work is made in such a way that it reveals its Maker by its very visibility, so that what is concealed may be known by looking at what is revealed. This is revealed so that everyone might believe that he is God, who made this cosmos, which is impossible for anyone else to do. Commentary on Paul’s Epistles.