As I read the Old Testament, I realize that there were also “gentiles” that believed in the true God of the Bible. Job, for instance, was not an Israelite, but was Jew, right? I constantly hear that the promises of the kingdom age are for Israel. Then what of the other Old testament saints? Are they included in that covenant?
Job came from the land of Uz, a large territory east of the Jordan, opposite what is now the Nation of Israel. Today this land belongs partly to Jordan and partly to Syria. After the Flood everyone on Earth was a follower of God again, and there were many who were not descendants of Abraham. Before the nation of Israel was formed in the wilderness, and its religious practices formalized into what we now call Judaism, they worshiped as believers had done since the fall, at altars they made themselves. Many believe Job lived in the time between Abraham and Moses and that his might be the first book of the Bible committed to writing.
From the time Judaism was first practiced, and all through its history, God made provisions for Gentiles who came to Him. Anyone who followed the practices of Judaism received the benefits of the covenant. Remember Jesus said that the Temple was intended to be a house of prayer for all nations, quoting Isaiah 56:5-7.
But the single qualification for salvation has been the same from the beginning, a belief that God would send a Redeemer to save them from their sins. The ways in which God has revealed Himself to man has changed over the Millennia but that fact has been consistent since the time of Adam.