Therefore glorify the LORD in the east, even the name of the LORD God of Israel in the coastlands of the sea.
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Cyril of Alexandria
AD 444
By “sea” he means the multitude of nations, and by “coastlands,” perhaps, he means cities. All their inhabitants will “raise their voices” when the divine wrath comes upon them. But the majesty of Christ will somehow be in the sea, that is, in all those nations, and they will realize that it is through divine Providence that they are destroyed and annihilated. They are destroyed because their impiety provoked the Almighty God; hence they will reject their gods who are unable to help them. That is how the majesty of the Lord is celebrated. It is clear that the purpose of the prophecy is to point to the mystery of Christ and to remind about the coming salvation in him.… Now, when the preaching of the holy apostles, which leads the nations from the idolatry to the grace of Christ, is spread to the ends of the earth, then, he says, “they shall cry aloud from the sea,” that is, all the nations of the world. - "Commentary on Isaiah 2.5.24"
“Therefore, the glory of the Lord is in the islands of the sea.” That pertains obviously to the church, which is located in the midst of the godless nations as if an island in the sea. It is in that island that the glory of the Lord shines. - "Commentary on Isaiah 7.19"
Instruction. The Church is like an island, compared with the rest of the world; or it preaches the gospel to all nations, and to the islands, like Great Britain. (Worthington)
Apostolic men are required to preach incessantly to all sorts of people. Hebrew, "in light "or Pagnin, "in vales. "(Menochius)
“And God remembered Babylon the great, who came into his sight.” This designates the confused multitude of all the lost. “That he might give it to drink from the wine of his wrath.” The retribution of due punishment to be returned to the wicked is here recorded. “And all the islands fled, and no mountains could be found.” I believe that these islands and mountains are literary figures for the church on account of the prominence of its stability, concerning which it is also said through Isaiah: “Glorify the Lord in doctrine, the name of the Lord God of Israel in the islands of the sea.” - "Commentary on the Apocalypse 4.16"