Isaiah 26:1-8 reads like a Psalm.  It also functions like a Psalm since it is designed to urge us to sing its words.  The fact that it begins, “In that day this song will be sung…”, means it functions like all biblical prophecy–it shows us a picture of the future to urge true Believers to sing it now.  So, because of our relationship to God through faith in Christ and the power of the Spirit, we can now sing about our existence in this strong city (v. 1), we can evaluate whether we are citizens who are allowed to enter God’s city of salvation (vv. 2, 4-6, 8), and also enjoy city life characterized by “perfect peace” and a “level” path (cf. vv. 3, 7).  Our Savior makes it all possible for us as He experienced on the Cross the humiliation expressed in vv. 5-6 for us.  The songs of Isaiah, like so many Psalms, are designed to be experienced by Believers.  We sing these words to the extent that we experience the status they describe.  Prophecy moves us to adopt this lifestyle of trust and obedience (cf. v. 8).

Isaiah 25 sounds like a Psalm of praise.  God’s people are exalting God because of all the “wonderful things” He has done for them.  After two expressions of intentions (“I will…I will…” in v. 1), a series of explanations (“For you have…”) make up the largest part of the praise-prophecy.  When you arrive at v. 6, the prophecy shifts to what the Lord will do.  Verses 6-8 present a quality of life that everyone wants to experience.  Isaiah is urging the Church to be sure they will be there in that day.  Verse 9 presents the condition: “…this is our God; we have waited for him…”  Isaiah intends for their future confession to be our confession now.

Isaiah 19:18-25 presents a bizarre look at “that day” when even some people from God’s notorious enemy nations will be saved.  Israel’s problem in Isaiah has been the tendency to trust the nation, Assyria, for help (cf. also 2 Kings 16:7).  In vv. 18-22 Isaiah shows us what will happen to some individuals because of God’s activity.  Verse 21 shows what they will do and their actions become an example for every Believer to follow.  Also important for the Church is to be sure that we will be in this trio of blessed people: Egypt, Assyria, and Israel.  Of course, that requires that we are working now with God in making Himself known to the nations.  It’s His mission; it’s our mission.  Remember that prophetic Texts are designed to drive us toward more holiness and faithfulness.  This picture of God’s future day is a day we participate in partially now because of Christ’s accomplishments.  It’s not just will Christians be in on that day, but how are we participating in part of that day now through faith in Christ.  This angle fits many Old and New Testament prophetic and visionary Texts.

Isaiah includes a huge section on the judgment of the nations (chapters 13-27) that is difficult to preach.  Look for reasons why judgment falls on them.  Isaiah is urging God’s people to not act like the nations so they will escape judgment.  In Isaiah 13:6-11 and 14:12-17 we encounter a description of the day of the Lord that’s coming, “cruel, with wrath and fierce anger…to destroy its sinners…” (13:9).  Then 14:12-17 contain the well-known claims of an egotistical king (“I will make myself like the Most High” v. 14).  As 2 Peter 3:1-13 states, all this talk about coming judgment is designed to urge God’s people to holiness.  All the pride of the king in 14:12-17 is contrasted by our Savior who “…humbled himself by becoming obedient to the point of death…” (cf. Phil. 2:5-8).  Believers respond to the prediction of future judgment by trusting and obeying their Savior.  Allow judgment Texts to spur us on to holiness.