Christians in the West are wondering just how God is at work their world today. North Americans are at a loss to explain why churches that used to be full are now in decline and why older models of evangelism and church growth seem less successful than anticipated. In response, Christians should seek to retrieve the Old Testament basis of their New Testament faith. Isaiah 56-66, sometimes called "Third Isaiah," belongs to a time when the people of Judea were under Persian rule—things were not as bad as they had been under Babylonian captivity, but not nearly as good as the "halcyon days" of the pre-exilic Kingdoms of Israel and Judah. They wondered why things were not better than they were, given the promises of restoration through other prophets. This book offers careful reflection on Isaiah 56-66 for Christian believers who face similar cultural issues: immigration and diaspora; national decline and an internationalizing setting; how to be faithful in difficult times; family, sexuality, and gender; economics and social justice; and more. Christian readers will explore the roots of their faith through concepts such as the Mosaic law, ritual purity and the sacrificial system, and predictive prophecy.