What does Isaiah 37:35 mean?

The Lord doesn't always clearly reveal His motives as He does in this verse. He has promised Hezekiah that Sennacherib and the Assyrians (Isaiah 36:1–3) will fail to harm Jerusalem in any way (Isaiah 37:33). In fact, Sennacherib will turn and go back where he came from (Isaiah 37:34). Instead of destruction, the Lord promised that the survivors of His people in Jerusalem would emerge from the city to thrive and repopulate the land. God been clear that He acts in response to Hezekiah's humble cry for help (Isaiah 37:14–15). However, another part of Hezekiah's prayer was for the Lord to defend His own name against Sennacherib's mockery and boasting (Isaiah 37:10–13).

Here, God repeats His plan to preserve Jerusalem. He does this to further His own will, and to honor the promise made to David (2 Samuel 7:8–16). Those reasons strike many readers as odd. Some object to the idea that the Lord would defend His people merely to boost His own prestige. Yet this is exactly what all of God's people should want Him to do. If our God is holy, righteous, powerful, and loving, those who already belong to Him want everyone to know that. It would be wrong for God not to glorify Himself or to defend His reputation in the world. Much of the Lord's purpose in creating the universe is to display His glory.

This moment serves as a dramatic opportunity to show the world that the God of Israel was the only true God in the entire world (Isaiah 45:5). The Assyrians' defeat of so many pagan nations revealed how powerless their wood and stone gods truly were (Deuteronomy 4:8; Psalm 115:4–8; Habakkuk 2:18–19). The Lord has used the Assyrians to prove that false gods were worthless, and to show His own people the impotence of the false gods they worshipped instead of Him (Isaiah 1:4; 2:6–8). Now the world would see that when God's people had literally nothing else on which to depend, He would easily defeat the feared Assyrian army (Isiaah 37:36–38). This would magnify God's name to both His people and the entire world.

God also acts to preserve His guarantees to David, the former king of Israel during her most glorious and faithful days (2 Samuel 5:3–5). God had a special relationship with David, called a man after God's own heart (1 Samuel 13:14). The Lord had promised David a throne established forever through his descendants (2 Samuel 7:12–13). It is this throne of David that Jesus the Messiah will take possess forever (Isaiah 9:7; Revelation 22:16).

As the Lord says He will save Jerusalem for David, He also implies that He is preserving the throne which will eventually be held by the Messiah in the eternal kingdom of the Lord. It's true that Jerusalem will be destroyed and the people exiled after a siege by the Babylonians about a century after the dramatic rescue recorded here (2 Chronicles 36:17–21). But the remnant of that exile will preserve their identity as Israelites and eventually return to occupy the land. Perhaps the Assyrians would have so thoroughly scattered the few remaining people of Judah that the line would have been lost had the Lord not stepped in to preserve David's throne and kingdom.