John Calvin Commentary Isaiah 30:12

"Wherefore thus saith the Holy One of Israel, Because ye despise this word, and trust in oppression and perverseness, and rely thereon;" — Isaiah 30:12 (ASV)

Because you have disdained this word. Next, he declares the punishment of ungodliness, threatening that they will not go unpunished for refusing to listen to God when He speaks; and he expresses their contempt more strongly by the word “disdain.” He calls it “this word,” using the demonstrative, because people would willingly devise some word suited to their way of life, but refuse to listen to God when He speaks.

And trusted in violence and wickedness. God’s gentle invitation, and His exhortation to quiet rest, are contrasted here with their disorderly pursuits. The Hebrew word עשק (gnōshĕk) denotes “robbery,” and “seizing property that belongs to another.” Others render it as “ill-gotten wealth.” Those who render it as “calumny” do not sufficiently express the Prophet’s meaning. For my own part, I do not view it as referring to riches gained by unlawful methods, but rather to that rebelliousness in which that nation insolently indulged.

The word “wickedness,” which is added, should not be limited to decisions of courts of law; because, in my opinion, it has a more extensive meaning. By these two words, he intended to express the presumption of wicked people. This presumption caused them to fiercely and wantonly rise up against God, as they always dared to follow their own lawless desires and do what was forbidden.

And just as the poets depict the giants making war with God, so these people resisted God’s threats, thinking they would quickly overcome His power by their fierceness and presumption.