John Calvin's Bible Commentary
Psalms 102:21
21That the name of Jehovah may be declared in Zion Here is celebrated a still more ample and richer fruit of this deliverance than has been previously mentioned, which is, that the Jews would not only be united into one body to give thanks to God, but that, when brought back to their own country, they would also gather kings and nations into the same unity of faith, and into the same divine worship with themselves. At that time it was a thing altogether incredible, not only that the praises of God should within a short period resound, as in the days of old, in that temple which was burnt and completely overthrown, (154) but also that the nations should resort thither from all quarters, and be associated together in the service of God with the Jews, who were then like a putrefied carcase. The prophet, to inspire the people with the hope of returning to their own land, argues that it was impossible that the place which God had chosen for himself should be left in perpetual desolation; and declares, that so far from this being the case there would be new matter for praising God, inasmuch as His name would be worshipped by all nations, and the Church would consist not of one nation only, but of the whole world. This we know has been fulfilled under the administration of Christ, as was announced in prophecy by the holy patriarch,
“The scepter shall not depart from Judah, nor a lawgiver from between his feet, until Shiloh come; and unto him shall the gathering of the Gentiles be, ” (Genesis 49:10.)
But as the prophets are wont, in celebrating the deliverance from the Babylonish captivity, to extend it to the coming of Christ, the inspired bard in this place does not lay hold on merely a part of the subject, but carries forward the grace of God, even to its consummation. And although it was not necessary that all who were converted to Christ should go up to Jerusalem, yet following the manner of expression usual with the prophets, he has laid down the observance of the divine worship which was appointed under the law, as a mark of true godliness. Farther, we may learn from this passage, that the name of God is never better celebrated than when true religion is extensively propagated, and when the Church increases, which on that account is called,
“The planting of the Lord, that he might be glorified,” (Isaiah 61:3.)