Thematic Bible: Who became vain

Therefore I say this, and witness in the Lord, that you no longer walk about as the Gentiles also walk about in the vanity of their mind, being darkened in their understanding, alienated from the life of God through the ignorance being in themselves, on account of the blindness of their heart; who being past feeling have given themselves up to debauchery, unto the working of all impurity with greediness.

For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men, who hold the truth in unrighteousness; because that which is known of God is manifest in them; for God has revealed it to them: for the invisible things of Him from the creation of the world are seen, being known by the things which are made, even His eternal power and divinity; so that they are without excuse: read more.
because, knowing God, they did not glorify Him as God, neither were they thankful; but they became vain in their reasonings, and their foolish heart was darkened. Saying that they were wise, they became fools, and changed the glory of the invisible God into the similitude of the likeness of corruptible man, and of birds, and of quadrupeds, and of creeping things.