What was the purpose of Israel's obedience to the Law at Mount Sinai?
Israel's obedience to the Sinai covenant would make the nation a mediator—a kingdom of priests and go-betweens—through whom God could funnel salvation to the Gentile world. God intended Israel to be a light to the Gentiles, raising up Jacob's tribes and restoring preserved Israel while extending that light beyond Israel.
Les explains that Isaiah 49:6 shows God's purpose for Israel: they were to be a nation of go-betweens, or priests. If they were obedient to the Law and the covenant God was giving them at Mount Sinai, then they would be God's channel sometime down the road to funnel salvation into the Gentile world. Even though God knew the nation would fall far short, these were valid offers. Israel was also to raise up the tribes of Jacob, restore the preserved of Israel, and be given as a light to the Gentiles.