Rom 11:7-12, Acts 28:23-28
In the Old Testament, Isaiah prophesied that God would prevent the people of Israel from understanding the gospel of God. (Isa 29:10-12)
Isa 29:10 For the Lord hath poured out upon you the spirit of deep sleep, and hath closed your eyes: the prophets and your rulers, the seers hath he covered. 11 And the vision of all is become unto you as the words of a book that is sealed, which men deliver to one that is learned, saying, Read this, I pray thee: and he saith, I cannot; for it is sealed: 12 And the book is delivered to him that is not learned, saying, Read this, I pray thee: and he saith, I am not learned.
As prophesied in the Old Testament, the Israelites did not understand the gospel of God, that is, Jesus was the Christ. So the gospel of God was delivered to the Gentiles. (Romans 11:7-12)
Romans 11:7 What then? Israel hath not obtained that which he seeketh for; but the election hath obtained it, and the rest were blinded. 8 (According as it is written, God hath given them the spirit of slumber, eyes that they should not see, and ears that they should not hear;) unto this day. 9 And David saith, Let their table be made a snare, and a trap, and a stumblingblock, and a recompence unto them: 10 Let their eyes be darkened, that they may not see, and bow down their back alway. 11 I say then, Have they stumbled that they should fall? God forbid: but rather through their fall salvation is come unto the Gentiles, for to provoke them to jealousy. 12 Now if the fall of them be the riches of the world, and the diminishing of them the riches of the Gentiles; how much more their fulness?
Paul explained to the many Jews who visited him in the Roman prison that the Old Testament was explaining the coming Christ and that that Christ was Jesus. But the Jews did not believe it, so the gospel of God was delivered to the Gentiles. (Acts 28:23-28)
Acts 28:23 And when they had appointed him a day, there came many to him into his lodging; to whom he expounded and testified the kingdom of God, persuading them concerning Jesus, both out of the law of Moses, and out of the prophets, from morning till evening. 24 And some believed the things which were spoken, and some believed not. 25 And when they agreed not among themselves, they departed, after that Paul had spoken one word, Well spake the Holy Ghost by Esaias the prophet unto our fathers, 26 Saying, Go unto this people, and say, Hearing ye shall hear, and shall not understand; and seeing ye shall see, and not perceive: 27 For the heart of this people is waxed gross, and their ears are dull of hearing, and their eyes have they closed; lest they should see with their eyes, and hear with their ears, and understand with their heart, and should be converted, and I should heal them. 28 Be it known therefore unto you, that the salvation of God is sent unto the Gentiles, and that they will hear it.