Study of ROMANS 1:18-25

18 For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men, who hold the truth in unrighteousness;
19 Because that which may be known of God is manifest in them; for God hath shewed it unto them. 20 For the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made, even his eternal power and Godhead; so that they are without excuse: 21 Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened. 22 Professing themselves to be wise, they became fools, 23 And changed the glory of the uncorruptible God into an image made like to corruptible man, and to birds, and fourfooted beasts, and creeping things. 24 Wherefore God also gave them up to uncleanness through the lusts of their own hearts, to dishonour their own bodies between themselves: 25 Who changed the truth of God into a lie, and worshipped and served the creature more than the Creator, who is blessed for ever. Amen

Ro 1:18. WHY THIS DIVINELY PROVIDED RIGHTEOUSNESS IS NEEDED BY ALL MEN.
18. For the wrath of God—His holy displeasure and righteous vengeance against sin.
is revealed from heaven—in the consciences of men, and attested by innumerable outward evidences of a moral government.
against all ungodliness—that is, their whole irreligiousness, or their living without any conscious reference to God, and proper feelings towards Him.
and unrighteousness of men—that is, all their deviations from moral rectitude in heart, speech, and behavior. (So these terms must be distinguished when used together, though, when standing alone, either of them includes the other).
Ro 1:18–32. THIS WRATH OF GOD, REVEALED AGAINST ALL INIQUITY, OVERHANGS THE WHOLE HEATHEN WORLD.
18. who hold—rather, “hold down,” “hinder,” or “keep back.”
the truth in unrighteousness—The apostle, though he began this verse with a comprehensive proposition regarding men in general, takes up in the end of it only one of the two great divisions of mankind, to whom he meant to apply it; thus gently sliding into his argument. But before enumerating their actual iniquities, he goes back to the origin of them all, their stifling the light which still remained to them. As darkness overspreads the mind, so impotence takes possession of the heart, when the “still small voice” of conscience is first disregarded, next thwarted, and then systematically deadened. Thus “the truth” which God left with and in men, instead of having free scope and developing itself, as it otherwise would, was obstructed (compare Mt 6:22, 23; Mt 6:22, 23, Eph 4:17, 18).
19. Because that which may be—rather, “which is.”
known of God is manifest in them; for God hath showed it unto them—The sense of this pregnant statement the apostle proceeds to unfold in Ro 1:20.
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.
21. Because that, when they knew God—that is, while still retaining some real knowledge of Him, and ere they sank down into the state next to be described.
they glorified him not as God, neither were thankful—neither yielded the adoration due to Himself, nor rendered the gratitude which His beneficence demanded.
but became vain—(compare Je 2:5).
in their imaginations—thoughts, notions, speculations, regarding God; compare Mt 15:19; Lu 2:35; 1Co 3:20, Greek.
and their foolish—“senseless,” “stupid.”
heart—that is, their whole inner man.
was darkened—How instructively is the downward progress of the human soul here traced!
22, 23. Professing themselves—“boasting,” or “pretending to be”
wise, they became fools—“It is the invariable property of error in morals and religion, that men take credit to themselves for it and extol it as wisdom. So the heathen” (1Co 1:21) [THOLUCK].
23. And changed—or “exchanged.”
the glory of the uncorruptible God into—or “for”
an image … like to corruptible man—The allusion here is doubtless to the Greek worship, and the apostle may have had in his mind those exquisite chisellings of the human form which lay so profusely beneath and around him as he stood on Mars’ Hill; and “beheld their devotions.” (See on Ac 17:29). But as if that had not been a deep enough degradation of the living God, there was found “a lower deep” still.
and to birds, and four-footed beasts, and to creeping things—referring now to the Egyptian and Oriental worship. In the face of these plain declarations of the descent of man’s religious belief from loftier to ever lower and more debasing conceptions of the Supreme Being, there are expositors of this very Epistle (as REICHE and JOWETT), who, believing neither in any fall from primeval innocence, nor in the noble traces of that innocence which lingered even after the fall and were only by degrees obliterated by wilful violence to the dictates of conscience, maintain that man’s religious history has been all along a struggle to rise, from the lowest forms of nature worship, suited to the childhood of our race, into that which is more rational and spiritual.
24. Wherefore God also—in righteous retribution.
gave them up—This divine abandonment of men is here strikingly traced in three successive stages, at each of which the same word is used (Ro 1:24; 26; and Ro 1:28, where the word is rendered “gave over”). “As they deserted God, God in turn deserted them; not giving them divine (that is, supernatural) laws, and suffering them to corrupt those which were human; not sending them prophets, and allowing the philosophers to run into absurdities. He let them do what they pleased, even what was in the last degree vile, that those who had not honored God, might dishonor themselves” [GROTIUS].
25. Who changed the truth of God into a lie—that is, the truth concerning God into idol falsehood.
and worshipped and served the creature more than the Creator—Professing merely to worship the Creator by means of the creature, they soon came to lose sight of the Creator in the creature. How aggravated is the guilt of the Church of Rome, which, under the same flimsy pretext, does shamelessly what the heathen are here condemned for doing, and with light which the heathen never had!
who is blessed for ever! Amen—By this doxology the apostle instinctively relieves the horror which the penning of such things excited within his breast; an example to such as are called to expose like dishonor done to the blessed God.