Acts 15:15-18
In the Old Testament, God said that He would save the remnant of Israel and the Gentiles who were called by His name. (Am 9:11-12)
Am 9:11 In that day will I raise up the tabernacle of David that is fallen, and close up the breaches thereof; and I will raise up his ruins, and I will build it as in the days of old: 12 That they may possess the remnant of Edom, and of all the heathen, which are called by my name, saith the Lord that doeth this.
According to the prophecy of the Old Testament, both Jews and Gentiles who believed in Jesus as the Christ were saved. (Acts 15:15-18)
Acts 15:15 And to this agree the words of the prophets; as it is written, 16 After this I will return, and will build again the tabernacle of David, which is fallen down; and I will build again the ruins thereof, and I will set it up: 17 That the residue of men might seek after the Lord, and all the Gentiles, upon whom my name is called, saith the Lord, who doeth all these things. 18 Known unto God are all his works from the beginning of the world.