Thursday of the Eighteenth Week in Ordinary Time
(Jeremiah 31:31-34; Matthew 16:13-23)
One of the greatest insights of Thomas Aquinas’ Summa Theologiae is contained in an article that refers to the first reading today. Near the end of the Prima Sacundae Thomas turns his attention from the Old Law to the New Law. He makes no fanfare as he treats of this entirely different kind of law, which is to the Old Law what a computer is to a typewriter.
Thomas says that the New Law fulfills the prophecy of Jeremiah that says it will be written on the hearts of God’s people. He understands this law to be not merely a list of rules or even a series of stories that illustrate righteousness. No, for Thomas and henceforth for the Catholic tradition the New Law is nothing less than the grace of the Holy Spirit that fills the hearts of those who believe in Jesus. It is as if the heart were given an entirely new shape, now designed to love as the old form was designed to seek personal satisfaction.
We express our belief in Jesus not just by testifying, as Peter does in today’s gospel that he is “the Christ, the Son of the living God,” but by following his commands. For Christians orthopraxis is as important as orthodoxy. But the challenge is not all that overwhelming because the grace of his Spirit is moving us to do so from within.