John Calvin Commentary Isaiah 24:15

"Wherefore glorify ye Jehovah in the east, even the name of Jehovah, the God of Israel, in the isles of the sea." — Isaiah 24:15 (ASV)

Therefore glorify Jehovah in the valleys. God’s benefits ought to excite us to gratitude, and we show it by singing His praises. “What return shall we make,” as David says, “for all the benefits which He has bestowed on us, but to take the cup of thanksgiving for salvation, and call on the name of the Lord?” The Prophet therefore observes this order; having spoken of the restoration of the Church, he exhorts us to offer the sacrifice of praise.

By the valleys, he means countries that are hidden and, as it were, separated from others; for those which are surrounded by mountains are separated and disjoined by nature. The consequence is that the inhabitants of valleys are less civilized, because they have fewer opportunities for interacting with each other. The meaning is the same as if the Prophet had said that there will not be a corner so obscure or secluded that the praises of God shall not be heard in it.

The name of Jehovah the God of Israel. He uses the expression, “the name of the God of Israel,” in order to indicate that all nations will call upon the true God; for, as all nations have a knowledge of God that is natural to them, so all easily turn aside to superstition and false worship (Romans 1:19). But here he speaks of spreading the true religion through the whole world; and this makes it still more evident that the prophecy relates to the kingdom of Christ, under which true religion has finally penetrated into foreign and Gentile nations.