Romans 1 19
God shows his anger because some knowledge of him has been made clear to them. Yes, God has shown himself to them.
Compare with other 3 random translations
FBV Romans 1:19What can be known about God is obvious, because he has made it very clear to them.
KJV Romans 1:19because that which may be known of God is manifest in them; for God hath showed it unto them.
ERV Romans 1:19This makes God angry because they have been shown what he is like. Yes, God has made it clear to them.