Isaiah 58

When people “worship” God in this way, then their light—the joy, the salvation, the full blessings of the Lord—will break forth (verse 8). Then the glory of the Lord will be their rear guard (see Isaiah 52:12); then the Lord will answer their prayers (verse 9). If God’s people will make loving their neighbor a way of life, then God will guide them, satisfy them, and strengthen them (verse 11). In short, they will receive all the physical and spiritual blessings promised to God’s obedient covenant people (Leviticus 26:3–13); they will be like a well-watered garden, like a spring whose waters never fail²¹⁴ (see John 7:37–38). And they will rebuild their city (verse 12). Here Isaiah is indirectly prophesying that Jerusalem will soon fall: it had to fall before it could be rebuilt!

13–14 Here again the Lord singles out the Sabbath law to be representative of all His laws (see Isaiah 56:2 and comment). To keep the Sabbath—to keep God’s law—is to show love for God. When we love Him in this way, we will find joy in the LORD; we will feast on the inheritance He has promised His faithful people: salvation and eternal life with Him (verse 14).

“True fasting”—true religion—is expressed in action (see James 1:27). Too many of us have only an external or ritualistic religion. The best way to test the genuineness of our religious faith is to examine the way we treat other human beings in need. That also happens to be the way God tests the genuineness of our faith! This is the primary message of this chapter.