How could an Old Testament person get back into a good relationship with God?
Under the law, an Old Testament person could not regain a good relationship with God by keeping the law, because the law only condemned. The way back was through the ritual and the sacrifices. The law itself could not accomplish it; it could only condemn, so those sacrifices were the avenue.
Les explains that the law could not save anyone; it only condemned. Jesus took the law even further, so that even thinking about sin meant it was broken. Under that Old Testament system, a person could not keep the law. The one exception was the ritual and the sacrifices, by which an Old Testament person could get back into a good relationship with God. But the law itself could not do it; it could only condemn. Les then contrasts this with the new circumstances: Christ has died, paid the sin debt, been buried, raised, ascended, and is interceding. The righteousness of God is now manifested without the law, witnessed by the law and the prophets—the Old Testament. Les insists the Old Testament must be taught alongside the New, because all Scripture dovetails together.