Often, the way a book of the Bible begins and ends will provide clues for what the book is intended to do. In the case of Isaiah, the purpose of our sermons can be seen in the description of God’s people in 1:2 (“but they have rebelled against me”) and the repeated refrain in 66:24 (“the men who have rebelled against me”). Let this emphasis determine the purpose of the middle of Isaiah. Throughout the book we’re encouraging all who come to worship to be sure they are truly worshiping God and not simply claiming to worship while rebelling against Him.