1 O praise the LORD, all ye nations: praise him, all ye people. 2 For his merciful kindness is great toward us: and the truth of the LORD endureth for ever. Praise ye the LORD.
Wherefore receive ye one another, as Christ also received us to the glory of God. Now I say that Jesus Christ was a minister of the circumcision for the truth of God, to confirm the promises made unto the fathers: And that the Gentiles might glorify God for his mercy; as it is written, For this cause I will confess to thee among the Gentiles, and sing unto thy name. And again he saith, Rejoice, ye Gentiles, with his people. And again, Praise the Lord, all ye Gentiles; and laud him, all ye people. [Psalms 117:1] And again, Esaias saith, There shall be a root of Jesse, and he that shall rise to reign over the Gentiles; in him shall the Gentiles trust. Now the God of hope fill you with all joy and peace in believing, that ye may abound in hope, through the power of the Holy Ghost.
"O praise the Lord, all you heathen: praise Him, all you nations" [Psalm 117:1]. These are the courts of the Lord's house, this all His people, this the true Jerusalem. Let those rather listen who have refused to be the children of this city, since they have cut themselves off from the communion of all nations. "For His merciful kindness is ever more and more towards us: and the truth of the Lord endures for ever" [Psalm 117:2]. These are those two things, loving-kindness and truth, which in the CXVth Psalm I admonished you should be committed to memory. But "the merciful kindness of the Lord is ever more and more towards us," since the furious tongues of hostile nations have yielded to His Name, through which we have been freed: "and the truth of the Lord endures for ever," whether in those things which He promised to the righteous, or in those which He has threatened to the ungodly.
Next comes, “And praise him highly, all you peoples.” High praise is the praise of all the faithful brought together as one; this is recognized to apply to the catholic church, which is gathered from various parts of the world. For all the Gentiles are generally reminded among their own peoples so that no one will say at the judgment of the Lord that he was passed over.
He added, “And the truth of the Lord remains forever.” Here “the truth” means “the Son of the Lord,” as he himself says, “I am the Way, the Truth, and the Life.” As the Arian3 (who is out of his mind) thinks, there was a time when the Son did not exist (it is awful even to say this!); that would mean that there was a time when the Father was without the Truth, without the Way and without the Life. But because the Father cannot be believed to have ever been without these things, it accords well with our salvation and the truth itself to confess that the Son is coeternal and of one substance with the Father in all things.
[AD 56] Romans on Psalms 117:1