Fasting and praying were common religious practices in the Israelite community that were associated with mourning and repentance. The first mention of these activities is in 2 Samuel 12:16 where it says that king David fasted and prayed because of his sick child. David wanted God to spare the child’s life, but his son died anyway.

Fasting was perceived to be a means of obtaining God’s mercy. As a form of spiritual intervention, it was effective in gaining God’s attention, although the desired result was not always obtained. Isaiah identified right and wrong types of fasting. One of the characteristics of the wrong type of fasting was an attitude of entitlement (Isaiah 58:3).

An indication that a person was fasting for the wrong reason was a desire for vengeance (Isaiah 58:4). The purpose of fasting was supposed to be to humble oneself before God (Isaiah 58:5). Speaking through Isaiah, the LORD declared, “Is not this the fast that I have chosen? to loose the bands of wickedness, to undo heavy burdens, and to let the oppressed go free, and that ye break every yoke?” (Isaiah 58:6).

Fasting was designed to be a tool to break free from spiritual bondage. Instead of focusing on their own spiritual condition, the Israelites had turned fasting into a speed dial to access God’s power. What God wanted was a sincere search for sin in one’s own life. His expectation was, “When thou see the naked that thou cover him, and that thou hide not thyself from thine own flesh” (Isaiah 58:7).

Evidence of genuine righteousness was important to God because he wanted his children to be an example for others. The LORD often referred to himself and his people as a light to the world. Regarding the practice of genuine righteousness, the LORD said, “then shall thy light break forth as the morning…then shall thy light rise in obscurity, and thy darkness be as the noonday” (Isaiah 58:8,10).

Ultimately, God wanted his people to demonstrate the results of following his commands, but in the near term, the goal was to show the world that God’s promises were reliable. After the people of Judah were taken into captivity in Babylon, a remnant was to return and rebuild Jerusalem. The remnant was going to be a group of true believers that would pave the way for the birth of Israel’s Messiah.

During their time in Babylon, the Israelites would be tested to see who among God’s people were truly committed to him. Those who were merely religious would not survive. Isaiah said of these true believers:

And the LORD shall guide thee continually, and satisfy thy soul in drought, and make fat thy bones: and thou shalt be like a watered garden, and  like a spring of water, whose waters fail not. And they that shall be of thee shall build the old waste places: thou shalt raise up the foundations of many generations; and thou shalt be called, The repairer of the breach, The restorer of paths to dwell in. (Isaiah 58:11-12)