What was Israel's purpose among the Gentile nations?
Israel was called out of the mainstream of humanity to become a kingdom of priests, prepared by the law, temple worship, and the Old Testament. Their purpose among the Gentile nations was to be funneled back into them to bring them to a knowledge of God, since Gentiles were outside the covenant, without hope and without God.
Les explains that God called Israel out of the mainstream of humanity and made promises that they would become a kingdom of priests. To prepare them for that role, He placed them under the law and gave them temple worship, the priesthood, and the Old Testament. Meanwhile, Gentiles were outside the covenant promises, not citizens of Israel, without hope and without God. They continued on their way until the time when Israel could be funneled back into the Gentile nations with the idea of bringing them to a knowledge of their God. This was the whole scope of the Old Testament, which is prophecy, telling future events including the death, burial, and resurrection of Christ, though in such subdued and latent terms that nobody understood it.