[LVI. Ben.]
On the Lord's Prayer in Matthew 6:9, etc. to the Competentes.
1. The blessed Apostle, to show that those times when it should come to pass that all the nations should believe in Christ had been foretold by the Prophets, produced this testimony where it is written, “And it shall be, that whosoever shall call on the name of the Lord, shall be saved.” For before time the name of the Lord who made heaven and earth was called upon among the Israelites only; the rest of the nations called upon dumb and deaf idols, by whom they were not heard, or by devils, by whom they were heard to their harm. “But when the fullness of time came,” that was fulfilled which had been foretold, “And it shall be, that whosoever shall call upon the name of the Lord, shall be saved.” Moreover, because the Jews, even those who believed in Christ, grudged the Gospel to the Gentiles, and said that the Gospel ought not to be preached to them who were not circumcised; because against these the Apostle Paul alleged this testimony, “And it shall be, that whosoever shall call upon the Name of the Lord, shall be saved;” he immediately subjoined, to convince those who were unwilling that the Gospel should be preached to the Gentiles, the words, “But how shall they call upon Him, in whom they have not believed? Or how shall they believe in Him of whom they have not heard? Or how shall they hear without a preacher? Or how shall they preach except they be sent?” Because then he said, “how shall they call upon Him in whom they have not believed?” you have not first learned the Lord's Prayer, and after that the Creed; but first the Creed, where ye might know what to believe, and afterwards the Prayer, where ye might know whom to call upon. The Creed then has respect to the faith, the Lord's Prayer to prayer; because it is he who believes, that is heard when he calls.
Source: Sermons on Selected Lessons of the New Testament (New Advent)