at he hearing comes because the gospel is preached by his followers that’s what Paul’s explainkng it’s an old prophecy that was fulfilled
“for, “Everyone who calls on the name of the Lord will be saved.”
How, then, can they call on the one they have not believed in? And how can they believe in the one of whom they have not heard? And how can they hear without someone preaching to them? And how can anyone preach unless they are sent?
As it is written: “How beautiful are the feet of those who bring good news!” ( prophecy ) Consequently, faith comes from hearing the message, and the message is heard through the word of Christ.”
Romans 10:13-15, 17 NIV
when a person hears this for instance
“For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.”
John 3:16
that information can now take root and begin to shape tbier faith . Until they hear that message they can’t believe it . You have to hear the message in order to believe or disregard it as foolishness
“How beautiful upon the mountains are the feet of him that bringeth good tidings, that publisheth peace; that bringeth good tidings of good, that publisheth salvation; that saith unto Zion, Thy God reigneth! Thy watchmen shall lift up the voice; with the voice together shall they sing: for they shall see eye to eye, when the LORD shall bring again Zion.
The LORD hath made bare his holy arm in the eyes of all the nations; and all the ends of the earth shall see the salvation of our God. Behold, my servant shall deal prudently, he shall be exalted and extolled, and be very high. As many were astonied at thee; his visage was so marred more than any man, and his form more than the sons of men: so shall he sprinkle many nations; the kings shall shut their mouths at him: for that which had not been told them shall they see; and that which they had not heard shall they consider.”
Isaiah 52:7-8, 10, 13-15 KJV
“Who hath believed our report? and to whom is the arm of the LORD revealed? Surely he hath borne our griefs, and carried our sorrows: yet we did esteem him stricken, smitten of God, and afflicted. But he was wounded for our transgressions, he was bruised for our iniquities: the chastisement of our peace was upon him; and with his stripes we are healed.( the heart of Paul’s message ) All we like sheep have gone astray; we have turned every one to his own way; and the LORD hath laid on him the iniquity of us all.
And he made his grave with the wicked, and with the rich in his death; because he had done no violence, neither was any deceit in his mouth. Yet it pleased the LORD to bruise him; he hath put him to grief: when thou shalt make his soul an offering for sin, he shall see his seed, he shall prolong his days, and the pleasure of the LORD shall prosper in his hand.”
Isaiah 53:1, 4-6, 9-10 KJV
Prophecy helps understand Paul a lot because his doctrine is directly coming from ot prophecy