Thematic Bible: Who became vain

This, therefore, I say, and testify in the Lord, that ye no longer walk as the gentiles also walk, in the vanity of their mind, being darkened in their understanding, alienated from the life of God because of the ignorance that is in them, because of the hardness of their hearts; who, indeed, having become without feeling, delivered themselves up to lasciviousness for the working of all uncleanness with greediness.

For God's wrath is revealed from Heaven against all ungodliness and unrighteousness of men, who hinder the truth in unrighteousness; because that which is known of God is manifested in them; for God manifested it to them. For His invisible things, since the creation of the world, are clearly seen, being perceived by the things that are made, even His everlasting power and divinity; that they may be without excuse: read more.
because, having known God, they did not glorify Him as God, nor did they give thanks; but they became vain in their reasonings, and their senseless heart was darkened. Professing themselves to be wise, they became fools, and changed the glory of the incorruptible God for the likeness of an image of corruptible man, and of birds, and quadrupeds, and reptiles.