What does Isaiah 25:4 mean?
This chapter started with a celebration of the Lord for His righteous acts of defeating those who oppose Him (Isaiah 25:1–3). Prideful people can become ruthless: willing to do whatever terrible things are required to defeat their enemies and take all the power for themselves. The clearest example of such people during Isaiah's time were the utterly merciless and cruel Assyrians.When the Lord reveals His limitless strength and power against such people, they are either destroyed or humbled and learn to fear Him. The strong people, those who submit willingly to the Lord, continue to give God glory. The point is not just that God will put arrogant, violent nations in their place. It's that the Lord also acts to protect the poor and needy because of His great concern for them (Psalm 9:9; 62:6). The vulnerable can run to the Lord and find refuge from those who will take advantage of them out in the world.
Weather is used as a metaphor in this section. When the storm hits, the Lord is a shelter. When the heat blasts, as it often does in the desert regions around Israel, the Lord is a shade. The Lord is worthy of praise because He exists to protect His people from harm. Within his metaphor, Isaiah describes the ruthless warriors as the storm and the heat. The Lord stands between them and those who depend on Him.