What added responsibility did people have after the Messiah appeared in the gospel accounts?
With the Messiah's appearance in the gospel accounts, an added responsibility was to believe that He was the Christ and the fulfillment of all the Old Testament covenants, while people were still required to keep the commandments and law under the Judaic system.
Les explains that in the gospel accounts, Israel was still to keep the commandments and the law, and that this was the salvation for that time. With the appearance of the Messiah, an added responsibility was to believe that He was the Christ, the fulfillment of all those 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 only gives the knowledge of sin and does nothing but condemn; it has no power to save anybody. Now the righteousness of God is without the Law, indicating a change from that Judaic system.