Thematic Bible: Who became vain

So this I say and solemnly testify in [the name of] the Lord [as in His presence], that you must no longer live as the heathen (the Gentiles) do in their perverseness [in the folly, vanity, and emptiness of their souls and the futility] of their minds. Their moral understanding is darkened and their reasoning is beclouded. [They are] alienated (estranged, self-banished) from the life of God [with no share in it; this is] because of the ignorance (the want of knowledge and perception, the willful blindness) that is deep-seated in them, due to their hardness of heart [to the insensitiveness of their moral nature]. In their spiritual apathy they have become callous and past feeling and reckless and have abandoned themselves [a prey] to unbridled sensuality, eager and greedy to indulge in every form of impurity [that their depraved desires may suggest and demand].

For God's [holy] wrath and indignation are revealed from heaven against all ungodliness and unrighteousness of men, who in their wickedness repress and hinder the truth and make it inoperative. For that which is known about God is evident to them and made plain in their inner consciousness, because God [Himself] has shown it to them. For ever since the creation of the world His invisible nature and attributes, that is, His eternal power and divinity, have been made intelligible and clearly discernible in and through the things that have been made (His handiworks). So [men] are without excuse [altogether without any defense or justification], read more.
Because when they knew and recognized Him as God, they did not honor and glorify Him as God or give Him thanks. But instead they became futile and godless in their thinking [with vain imaginings, foolish reasoning, and stupid speculations] and their senseless minds were darkened. Claiming to be wise, they became fools [professing to be smart, they made simpletons of themselves]. And by them the glory and majesty and excellence of the immortal God were exchanged for and represented by images, resembling mortal man and birds and beasts and reptiles.