How did God plan to bring salvation to the Gentiles in the Old Testament?
God planned to reach the Gentiles through Israel, His covenant people, all through the Old Testament. Israel was to be the channel taking His salvation to the Gentiles. Scripture foretold the Messiah, God's servant, would be a light to the Gentiles and God's salvation to the end of the earth.
Les teaches that God was only planning to deal with the Gentiles all the way up through the Old Testament through this covenant people, Israel. They were going to be the ones who would take salvation to the Gentiles. In Isaiah 42, the singular servant—God's elect, upon whom He put His Spirit—would bring forth judgment or rule to the Gentiles, and Les identifies this servant as the Christ, the Messiah. Then in Isaiah 49:6-7, God says it is a light thing for the servant to raise up the tribes of Jacob and restore the preserved of Israel; He will also give him as a light to the Gentiles. God's mind was set on Israel taking His light to the Gentiles, and His salvation would reach to the end of the earth.