Paul addresses the points you raised regarding the Jewish expectations of Messiah and the reality that the law must be written on the hearts (in the Person of His Holy Spirit indwelling the human spirit) for no man can keep the whole law blameless, with his letter to the Romans and in his first letter to the Church at Corinth. As to the Jews, their current blindness serves God's purposes. He will lift the scales from their minds in His own good timing.
No man can keep the whole law blameless, but he can try. You can honestly try even if you honestly fail. The intent matters.