Because that - The apostle here is showing that it was right to condemn people for their sins. To do this it was needful to show them that they had the knowledge of God, and the means of knowing what was right; and that the true source of their sins and idolatries was a corrupt and evil heart.

When they knew God - Greek, "knowing God." That is, they had an acquaintance with the existence and many of the perfections of one God. That many of the philosophers of Greece and Rome had a knowledge of one God, there can be no doubt. This was undoubtedly the case with Pythagoras, who had traveled extensively in Egypt, and even in Palestine; and also with Plato and his disciples. This point is clearly shown by Cudworth in his Intellectual System, and by Dr. Warburton in the Divine Legation of Moses. Yet the knowledge of this great truth was not communicated to the people. It was confined to the philosophers; and not improbably one design of the mysteries celebrated throughout Greece was to keep up the knowledge of the one true God. Gibbon has remarked that "the philosophers regarded all the popular superstitions as equally false: the common people as equally true; and the politicians as equally useful." This was probably a correct account of the prevalent feelings among the ancients. A single extract from "Cicero" (de Natura Deorum, lib. ii. c. 6) will show that they had the knowledge of one God. "There is something in the nature of things, which the mind of man, which reason, which human power cannot effect; and certainly what produces this must be better than man. What can this be called but "God?" Again (c. 2), "What can be so plain and manifest, when we look at heaven, and contemplate heavenly things, as that there is some divinity of most excellent mind, by which these things are governed?"

They glorified him not as God - They did not "honor" him as God. This was the true source of their abominations. To glorify him "as God" is to regard with proper reverence all his perfections and laws; to venerate his name, his power, his holiness, and presence, etc. As they were not inclined to do this, so they were given over to their own vain and wicked desires. Sinners are not willing to give honor to God, as God. They are not pleased with his perfections; and therefore the mind becomes fixed on other objects, and the heart gives free indulgence to its own sinful desires. A willingness to honor God as God - to reverence, love, and obey him, would effectually restrain people from sin.

Neither were thankful - The obligation to be "thankful" to God for his mercies, for the goodness which we experience, is plain and obvious. Thus, we judge of favors received of our fellow-men. the apostle here clearly regards this unwillingness to render gratitude to God for his mercies as one of the causes of their subsequent corruption and idolatry. The reasons of this are the following.

(1) the effect of ingratitude is to render the heart hard and insensible.

(2) people seek to forget the Being to whom they are unwilling to exercise gratitude.

(3) to do this, they fix their affections on other things; and hence, the pagan expressed their gratitude not to God, but to the sun, and moon, and stars, etc., the mediums by which God bestows his favors upon people. And we may here learn that an unwillingness to thank God for his mercies is one of the most certain causes of alienation and hardness of heart.

But became vain - To "become vain," with us, means to be elated, or to be self-conceited, or to seek praise from others. The meaning here seems to be, they became foolish, frivolous in their thoughts and reasonings. They acted foolishly; they employed themselves in useless and frivolous questions, the effect of which was to lead the mind further and further from the truth respecting God.

Imaginations - This word means properly "thoughts," then "reasonings," and also "disputations." Perhaps our word, "speculations," would convey its meaning here. It implies that they were unwilling to honor God, and being unwilling to honor him, they commenced those speculations which resulted in all their vain and foolish opinions about idols, and the various rites of idolatrous worship. Many of the speculations and inquiries of the ancients were among the most vain and senseless which the mind can conceive.

And their foolish heart - The word "heart" is not infrequently used to denote the mind, or the understanding. We apply it to denote the affections. But such was not its common use, among the Hebrews. We speak of the head when we refer to the understanding, but this was not the case with the Hebrews. They spoke of the heart in this manner, and in this sense it is clearly used in this place; see Ephesians 1:18; Romans 2:15; 2 Corinthians 4:6; 2 Peter 1:19. The word "foolish" means literally what is without "understanding;" Matthew 15:16.

Was darkened - Was rendered obscure, so that they did not perceive and comprehend the truth. The process which is stated in this verse is,

(1) That people had the knowledge of God.

(2) that they refused to honor him when they knew him, and were opposed to his character and government.

(3) that they were ungrateful.

continued...

Because that when they knew God - When they thus acquired a general knowledge of the unity and perfections of the Divine nature, they glorified him not as God - they did not proclaim him to the people, but shut up his glory (as Bishop Warburton expresses it) in their mysteries, and gave the people, in exchange for an incorruptible God, an image made like to corruptible man. Wherefore God, in punishment for their sins, thus turning his truth into a lie, suffered even their mysteries, which they had erected for a school of virtue, to degenerate into an odious sink of vice and immorality; giving them up unto all uncleanness and vile affections.

They glorified him not - They did not give him that worship which his perfections required.

Neither were thankful - They manifested no gratitude for the blessings they received from his providence, but became vain in their imaginations, διαλογισμοις, in their reasonings. This certainly refers to the foolish manner in which even the wisest of their philosophers discoursed about the Divine nature, not excepting Socrates, Plato, or Seneca. Who can read their works without being struck with the vanity of their reasonings, as well as with the stupidity of their nonsense, when speaking about God? I might crowd my page with proofs of this; but it is not necessary to those who are acquainted with their writings, and to others it would not be useful. In short, their foolish, darkened minds sought God no where but in the place in which he is never to be found; viz. the vile, corrupted, and corrupting passions of their own hearts. As they did not discover him there, they scarcely sought him any where else.

Because that when they knew God,.... Though they had such a knowledge of the being and perfections of God, yet

they glorified him not as God. They neither thought nor spoke honourably of him; nor did they ascribe those perfections to him, which belonged to him; they did not adhere to him as the one and only God, nor honour him as the Creator of all things out of nothing, and as the sole Governor of the universe; they did not glorify him by the internal exercise of fear of him, love to him, or trust in him, nor by any external worship suitable to his nature, and their own notions of him, Seneca is an instance of this, of whom Austin (f) says,

"that he worshipped what he found fault with, did what he reproved, and adored that which he blamed.''

Neither were thankful; neither for the knowledge of things they had, which they ascribed to themselves; nor for their mercies, which they imputed to second causes:

but became vain in their imaginations; the vanity or their minds was the spring and source of their evil conduct; which may design the wickedness of their hearts, and the imaginations thereof, which were evil, and that continually; the pride of their natures the carnality and weakness of their reasonings, and the whole system of their vain philosophy; and hence they ran into polytheism, or the worshipping of many gods:

and their foolish heart was darkened; where they thought their great wisdom lay: darkness is natural to the hearts and understandings of all men, which is increased by personal iniquity; Satan is concerned in improving it, and God sometimes gives up the hearts of persons to judicial blindness, which was the case of these men.

(f) De Civitate Dei, l. 6. c. 10.

Knowing - glorified not

"I think it may be proved from facts that any given people, down to the lowest savages, has at any period of its life known far more than it has done: known quite enough to have enabled it to have got on comfortably, thriven and developed, if it had only done what no man does, all that it knew it ought to do and could do" (Charles Kingsley, "The Roman and the Teuton").

Became vain (ἐματαιώθησαν)

Vain things (μάταια) was the Jews' name for idols. Compare Acts 4:15. Their ideas and conceptions of God had no intrinsic value corresponding with the truth. "The understanding was reduced to work in vacuo. It rendered itself in a way futile" (Godet).

Imaginations (διαλογισμοῖς)

Rev., better, reasonings. See on Matthew 15:19; see on Mark 7:21; see on James 2:4.

Foolish (ἀσύνετος)

See on συνετός prudent, Matthew 11:25, and the kindred word σύνεσις understanding, see on Mark 12:33; see on Luke 2:47. They did not combine the facts which were patent to their observation.

Heart (καρδία)

The heart is, first, the physical organ, the center of the circulation of the blood. Hence, the seat and center of physical life. In the former sense it does not occur in the New Testament. As denoting the vigor and sense of physical life, see Acts 14:17; James 5:5; Luke 21:34. It is used fifty-two times by Paul.

Never used like ψυχή, soul, to denote the individual subject of personal life, so that it can be exchanged with the personal pronoun (Acts 2:43; Acts 3:23; Romans 13:1); nor like πνεῦμα spirit, to denote the divinely-given principle of life.

It is the central seat and organ of the personal life (ψυχή) of man regarded in and by himself. Hence it is commonly accompanied with the possessive pronouns, my, his, thy, etc.

Like our heart it denotes the seat of feeling as contrasted with intelligence. 2 Corinthians 2:4; Romans 9:2; Romans 10:1; 2 Corinthians 6:11; Philippians 1:7. But it is not limited to this. It is also the seat of mental action, feeling, thinking, willing. It is used -

1. Of intelligence, Romans 1:21; 2 Corinthians 3:15; 2 Corinthians 4:6; Ephesians 1:18.

continued...

Because that, when they knew God, they {e} glorified him not as God, neither were thankful; but became {f} vain in their imaginations, and their foolish heart was darkened.

(e) They did not honour him with that honour and service which was appropriate for his everlasting power and Godhead.

(f) As if he said, became so corrupt in themselves.

1:21 When they knew God. Had the knowledge shown in Ro 1:20. They turned from their knowledge, did not glorify the invisible Creator, yielded neither adoration nor gratitude.

Became vain in their imaginations. Thoughts or reasonings. When men turn willfully from truth, they will run to the extremes of error. The world (the pagan world) yielded to idle fancies, and were involved in deeper darkness. He who shuts out the light will finally be unable to bear it.

Vain. Empty, useless. See De 32:21.

1:21 Because, knowing God - For the wiser heathens did know that there was one supreme God; yet from low and base considerations they conformed to the idolatry of the vulgar. They did not glorify him as God, neither were thankful - They neither thanked him for his benefits, nor glorified him for his divine perfection. But became vain - Like the idols they worshipped. In their reasonings - Various, uncertain, foolish. What a terrible instance have we of this in the writings of Lucretius! What vain reasonings, and how dark a heart, amidst so pompous professions of wisdom!

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 Jer 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!

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.