What was the purpose of Israel's priesthood?
Israel's priesthood was intended to serve as a go-between between man and God, with every Jew becoming a priest of God to bring pagan Gentiles to a knowledge of their God. This was promised in Exodus 19, conditioned on Israel's obedience, as a nation of priests.
Les teaches that after God brought Israel out of Egypt, they were His covenanted people, and He told them that if they would be obedient and be what He wanted, they would be a nation of priests. A priest is a go-between between man and God. So every Jew was intended at some future day to become a priest of God to bring all these pagan Gentiles to a knowledge of their God. This priestly role was tied to the promise in Exodus 19 and to the prophetic timeline where Christ could have set up His kingdom and Israel could have been the priests they were promised to be. Les notes that all Old Testament prophecies run continuously concerning Israel through the 490 years.