It was God's purpose that His grace should be revealed among the Gentiles as well as among the Israelites. This had been plainly outlined in Old Testament prophecies. The apostle uses some of these prophecies in his argument. "Hath not the potter power over the clay," he inquires, "of the same lump to make one vessel unto honor, and another unto dishonor? What if God, willing to show His wrath, and to make His power known, endured with much long-suffering the vessels of wrath fitted to destruction: and that He might make known the riches of His glory on the vessels of mercy, which He had afore prepared unto glory, even us, whom He hath called, not of the Jews only, but also of the Gentiles? As He saith also in Osee, I will call them My people, which were not My people; and her beloved, which was not beloved. And it shall come to pass, that in the place where it was said unto them, Ye are not My people; there shall they be called the children of the living God." See Hosea 1:10.

Det var Guds formål, at hans nåde skulle åbenbares såvel blandt hedninger som blandt jøder. Dette var blevet tydeligt skitseret i gammeltestamentlige profetier. Apostlen benytter nogle af disse profetier i sin bevisførelse. "Har pottemageren ikke rådighed over sit ler," spørger han, "så han af den samme masse kan danne et kar til ære, et andet til vanære? Men hvad om nu Gud, skønt han vil vise sin vrede og kundgøre sin magt, dog i megen langmodighed har båret over med vredens kar, fuldt færdige til fortabelse og gjort dette også for at kundgøre sin herligheds rigdom over barmhjertighedens kar, som han forud havde beredt til herlighed? Og til at være sådanne kaldte han også os, ikke alene dem af jødisk, men tillige dem af hedensk æt, som han også siger hos Hoseas: