See, they are all a delusion; their works amount to nothing; their images are as empty as the wind.
29. Behold, they are all vanity. After having spoken of idols, he makes the same statement as to their worshippers; as it is also said, “They who make them, and all that trust in them, are like them.” (Psalm 115:8.) Thus he shews that all superstitious persons are full of “vanity,” and have no judgment or reason.
The Lord, by the prophet, here repeats the challenge to idolaters to make out the pretentions of their idols: "Produce your cause (Isa 41:21) and make your best of it; bring forth the strongest reasons you have to prove that your idols are gods, and worthy of your adoration." Note, There needs no more to show the absurdity of sin than to produce the reasons...
Commenting on Isaiah 41:21-29
Behold, they are all vanity,.... Both the idols and the worshippers of them; in vain they claim the title of deity, to which they have no right; and in vain do men worship them, since they receive no benefit by them: their works are nothing; they can do nothing, neither good nor evil; nothing is to be hoped or feared from them, and the worship...