1:18-25 The apostle begins to show that all mankind need the salvation of the gospel, because none could obtain the favour of God, or escape his wrath by their own works. For no man can plead that he has fulfilled all his obligations to God and to his neighbour; nor can any truly say that he has fully acted up to the light afforded him. The sinfulness of man is described as ungodliness against the laws of the first table, and unrighteousness against those of the second. The cause of that sinfulness is holding the truth in unrighteousness. All, more or less, do what they know to be wrong, and omit what they know to be right, so that the plea of ignorance cannot be allowed from any. Our Creator's invisible power and Godhead are so clearly shown in the works he has made, that even idolaters and wicked Gentiles are left without excuse. They foolishly followed idolatry; and rational creatures changed the worship of the glorious Creator, for that of brutes, reptiles, and senseless images. They wandered from God, till all traces of true religion must have been lost, had not the revelation of the gospel prevented it. For whatever may be pretended, as to the sufficiency of man's reason to discover Divine truth and moral obligation, or to govern the practice aright, facts cannot be denied. And these plainly show that men have dishonoured God by the most absurd idolatries and superstitions; and have degraded themselves by the vilest affections and most abominable deeds.
20. For the invisible things of him from—or "since"
the creation of the world are clearly seen—the mind brightly beholding what the eye cannot discern.
being understood by the things that are made—Thus, the outward creation is not the parent but the interpreter of our faith in God. That faith has its primary sources within our own breast (Ro 1:19); but it becomes an intelligible and articulate conviction only through what we observe around us ("by the things which are made," Ro 1:20). And thus are the inner and the outer revelation of God the complement of each other, making up between them one universal and immovable conviction that God is. (With this striking apostolic statement agree the latest conclusions of the most profound speculative students of Theism).
even his eternal power and Godhead—both that there is an Eternal Power, and that this is not a mere blind force, or pantheistic "spirit of nature," but the power of a living Godhead.
so that they are without excuse—all their degeneracy being a voluntary departure from truth thus brightly revealed to the unsophisticated spirit.