When the Messiah appeared, what additional responsibility was added to keeping the law?
With the Messiah’s appearance, an added responsibility was to believe that He was the Christ and the fulfillment of all the Old Testament covenants. That belief was added to keeping the law, yet salvation at that time was still based on the Judaic system of law.
Les explains that the people in the gospel accounts were to keep the commandments and the law, and within that was salvation for that time. With the appearance of the Messiah, an added responsibility was to believe that He was the Christ and the fulfillment of all the Old Testament covenants, but it was still based on the Judaic system of law. Later, Paul says that by the law there is no justification, for the law gives the knowledge of sin and only condemns; it has no power to save anybody. Les contrasts this with the change indicated in Romans 3:21: now the righteousness of God is without the Law, and we are no longer under that Judaic system of the Law.