Sometimes we consider the Law as something that imposes on us, that limits us. Thus the Law becomes something constricting and undesirable. But Moses tells us in today's first reading that if we observe the Law that God had enjoined us to follow, we are to have life and take possession of the land. Then the Law does not put a heavy burden on our shoulders. On the contrary, it frees us, for it teaches us how to have life. And what is this land that we are to possess? This land is the kingdom of God; and we are in the kingdom if we possess Christ.
Even before Christ came as man, the Law had the purpose of carrying out the divine plan for humanity. And then Christ came - to complete the Law, bringing it to perfection. It is basically still the same Law but brought to a higher realm. We will understand this with greater clarity when we read the rest of this chapter of Matthew, which is part of the Sermon on the Mount. For instance, Jesus gives us the same Law of love but introduces to us the love for the enemy. Aside from this, he imparts to us the Law with the accompanying grace to fulfill it. Therefore, let us not be afraid if Christ gives us the Law, which, seemingly, is impossible to fulfill for he grants us his Spirit. And if we possess his Spirit, the law can be accomplished in our lives.
We Christians are blessed to be given the new Law by Christ. As Ps 147 says, "He reveals his word to Jacob, his statutes and rulings to Israel." He did not reveal them to others but to us, the new Israel, his chosen ones. When we discover the sweetness of the Law and consider it a delight, then we will understand why we are blessed to possess it. Many times, however, it still seems like a burden to us, something too demanding considering our weakness.
Let us not be disheartened whenever we fail to keep the law, for as St. Paul says in the letter to the Romans, "However great the number of sins committed, grace was even greater." We can count on Christ's infinite mercy which is accompanied by his grace. That is why, for Christ, the Law is not one of moralizing but of giving freedom.