Isaiah’s aim is to draw the heart of disobedient Judah back to God. Toward the end of his great prophetic book, he acknowledges that his people are religious. “They seek me daily,” the Lord says, “and delight to know my ways, as if they were a nation that did righteousness and did not forsake the ordinance of their God; they ask of me righteous judgments, they delight to draw near to God. ‘Why have we fasted, and thou seest it not? Why have we humbled ourselves, and thou takest no knowledge of it?'” (Isa. 58:2-3).
Yes, the people of Judah fast, bowing their heads like bulrushes yielding to the wind and spreading sackcloth and ashes under them (Isa. 58:5). But this outward display of humility and sincerity brings them no closer to God. Isaiah explains that “in the day of your fast you seek your own pleasure, and oppress all your workers. […] Fasting like yours this day will not make your voice to be heard on high” (vs. 3-4). The fast God wants is a change of attitude. The prophet demands that his readers free the oppressed, share food with the hungry, give shelter to the homeless poor, and provide the needy with clothing (vs. 6-7).
This teaching is still relevant in 2017. Like the people of Isaiah’s day, we may be satisfied with an outward display of humility. Perhaps we assemble dutifully for worship and bow our heads in reverent prayer — only to resume our sinful thoughts and ways after the last Amen. If so, we must take the prophet’s sober warnings to heart. He says that “the Lord’s hand is not shortened, that it cannot save, or his ear dull, that it cannot hear; but your iniquities have made a separation between you and your God, and your sins have hid his face from you so that he does not hear” (Isa. 59:1-2).