Professing themselves to be wise they became fools.
The follies of the wise
Futility of thought has reached the character of folly. What, in fact, is polytheism, except a sort of permanent hallucination, a collective delirium, a possession on a great scale? And this mental disorder rose to a kind of perfection among the very peoples who, more than others, laid claim to the glory of wisdom. When he says, “professing to be wise,” Paul does not mean to stigmatise ancient philosophy absolutely; he only means that all that labour of the sages did not prevent, the most civilised nations--Egypt, Greece, and Rome--from being at the same time the most idolatrous of antiquity. The popular imagination, agreeably served by priests and poets, did not allow the efforts of the wise to dissipate this delirium. (Prof. Godet.)
Boasting of wisdom
In every department of knowledge, but especially in religion, boasting of wisdom is alike the proof and parent of folly.
I. It leads a man to go beyond the limits of his own powers, and to meddle with matters too high for him, or else to refuse to believe in anything which he cannot understand or grasp.
1. In either case this ends in folly. For the wisest and the most ignorant are on a par when they speculate upon subjects which transcend human thought, or over which God has been pleased to place an impenetrable veil.
2. He who believes in truth taught by nature and revelation is wiser than the so-called philosopher, who declines to receive anything but what his human intellect and finite powers can explain or fully grasp.
II. It leads a man to dispense with the help to be derived from the labours, remarks, or suggestions of others, as well as to advance the most absurd opinions, and to maintain them with the most inveterate obstinacy for the sake of notoriety.
III. It makes a man too willing to accept his own conclusions without sufficient and searching examinations.
IV. It ignores God’s law that the temple of Divine knowledge must be entered only by the gate of humility. (Biblical Museum.)
And changed the glory of the incorruptible God into an image.
Degradation of God’s glory
The glory of God is the splendour which His manifested perfections cast into the heart of His intelligent creatures; hence a bright image which is to man the ideal of all that is good. This image had been produced within them. What did they make of it? The sequel tells. While holding the Divine person, they wrapped it up, as it were in the likeness of its opposite; it would have been almost better to leave it in silence--it would not have been so great an affront. The preposition ἐν exactly describes this imprisonment of the Divine glory in a form ignoble and grotesque. The epithet “incorruptible” is, as it were, a protest beforehand against this degradation. (Prof. Godet.)
Idolatry a retrogression, not an advance in religious though
Idolatry according to Paul is not a progressive stage reached in the religious thought of mankind starting from primeval fetishism. Far from being a first step towards the goal of Monotheism. Polytheism is, on the contrary, the result of degeneracy, an apostasy from the original Monotheism, a darkening of the understanding and heart which has terminated in the grossest fetishism. The history of religions, thoroughly studied nowadays, fully justifies Paul’s view. It shows that the present heathen peoples of India and Africa, far from rising of themselves to a higher religious state, have only sunk, age after age, and become more and more degraded. It proves that at the root of all pagan religions and mythologies there lies an original Monotheism, which is the historical starting point in religion for all mankind. (Prof. Godet.)