Commentaries
2:1-8 Those who begin well, but do not persevere, will justly be upbraided with their hopeful and promising beginnings. Those who desert religion, commonly oppose it more than those who never knew it. For this they could have no excuse. God's spiritual Israel must own their obligations to him for safe conduct through the wilderness of this world, so dangerous to the soul. Alas, that many, who once appeared devoted to the Lord, so live that their professions aggravate their crimes! Let us be careful that we do not lose in zeal and fervency, as we gain knowledge.
5. iniquity—wrong done to them (Isa 5:4; Mic 6:3; compare De 32:4).
walked after vanity—contrasted with "walkest after me in the wilderness" (Jer 2:2): then I was their guide in the barren desert; now they take idols as their guides.
vanity … vain—An idol is not only vain (impotent and empty), but vanity itself. Its worshippers acquire its character, becoming vain as it is (De 7:26; Ps 115:8). A people's character never rises above that of its gods, which are its "better nature" [Bacon] (2Ki 17:15; Jon 2:8).