Adam Clarke on Romans 1:20

The invisible things of him - His invisible perfections are manifested by his visible works, and may be apprehended by what he has made; their immensity showing his omnipotence, their vast variety and contrivance, his omniscience; and their adaptation to the most beneficent purposes, his infinite goodness and philanthropy.

His eternal power - αιδιος αυτου δυναμις, That all-powerful energy that ever was, and ever will exist; so that, ever since there was a creation to be surveyed, there have been intelligent beings to make that survey.

And Godhead - θειοτης, His acting as God in the government and support of the universe. His works prove his being; the government and support of these works prove it equally. Creation and providence form a twofold demonstration of God, 1st. in the perfections of his nature; and, 2ndly. in the exercise of those perfections.