Yesterday we saw that “God rewards fasting because fasting expresses the cry of the heart that nothing on the earth can satisfy our souls besides God” (John Piper, A Hunger for God, p. 181). The practice never obligates the Lord to respond to our prayer precisely as we have asked. Nevertheless, just as when we first admitted our inability to save ourselves and called on Christ to redeem us, God is pleased when we put ourselves in a more helpless state by forgoing food because it displays how we are aware of our need for His grace at every stage of our lives.
Fasting among the pagan peoples who surrounded the ancient Israelites was far different. The followers of these religions thought they could obligate their gods to behave in specific ways if they fasted. Unsurprisingly, many Israelites adopted this belief in relation to their covenant Lord just as they had adopted other Canaanite beliefs , adding Baal and other foreign deities as objects of worship (Jer. 9:12–16; Hos. 2:13). We see an example of how many ancient Israelites believed their fasting could make God do their bidding in Isaiah 58:1–12. In verse 3, the prophet puts into writing the complaints he has heard from the people. As it says, the people were perplexed as to why their fastings had gone unnoticed by the Lord; that is, they wanted to know why He had not intervened on their behalf.
Aside from the fact that the sovereign creator God is by no means under any compulsion to respond to the fasts of His people as they might like, Isaiah gives another reason why Israel’s fast had been ignored. Verses 6–12 explain that the kind of fast the Lord wanted from His children was not merely the forgoing of food, but the end of wickedness and oppression, as well as providing for the needs of the poor and hungry. It is not that God wanted to abolish the practice of fasting altogether; He only desired the Israelites to have more than a surface-level piety. Apparently, the people refused to release their debtors as prescribed in Deuteronomy 15:1–2. They were praying and fasting, which was easy, but not obeying the harder command to forgive debts. No amount of fasting could help while they held onto this grave sin without repenting. God’s people should not expect Him to answer their fasting and prayer as long as they knowingly and obstinately refuse to repent and follow His will.