With a threat He forbade them to touch either way of life. He strictly required that they fulfill only His commandments and judgments.
“I am the Lord your God. You shall keep all My commandments and all My judgments, and do them. The man who does these things shall live by them” (cf. Lev 18:5).
Those nations, because of their impiety and evil life, would undergo punishments. But you will live in prosperity and safety (see Lev 18:25).
When He said “all,” He left no room for any exception. Fulfill everything, and you will be righteous according to legal righteousness, and you will live.
The Apostle makes no inferences. By the words of the Law itself he only shows what legal righteousness requires.
He “shows wherein legal righteousness consists and by what it is acquired. In what does it consist, and by what is it acquired? By the fulfillment of the Law. One cannot become righteous according to the Law otherwise than by fulfilling all the commandments” (Chrysostom).
Thus speaks the Law concerning legal righteousness. But its definitions of righteousness are not limited to this. In it there are indications concerning righteousness that are unthinkable and cannot come into effect unless faith enters.
In Deuteronomy (see Deut 30), in the concluding address to the people, God says through Moses that if they fulfill all His commandments, it will be well with them.
If they do not, calamity after calamity will befall them. But if, after provoking Him to wrath, they turn to Him again, then they will again be received into mercy.
Even if they have been scattered into distant lands, they will again be gathered into the inheritance of their fathers. For by these afflictions “the Lord will cleanse your heart, to love the Lord your God with all your heart and with all your soul” (cf. Deut 30:6).
Having thus fenced faithfulness to the Law with threats, God then removes every excuse for failing to fulfill it. Someone might make such an excuse because of the difficulty of knowing the Law.
He might also appeal to the burden of the Law itself, imposed like a yoke. “This commandment which I command you today,” and before this it was said that you should turn to the Lord your God with all your heart and soul (cf. Deut 30:10), “is not hard, nor is it far from you. It is not in heaven, that one should say, ‘Who will go up to heaven for us, and take it for us, that we may hear it and do it?’ Nor is it beyond the sea, that one should say. ‘Who will cross to the other side of the sea for us, and take it for us, that we may hear it and do it?’ The word is very near you, in your mouth, in your heart, and in your hand, that you may do it” (cf. Deut 30:11-14).
In these words one thing is indicated that was before their eyes, and another that was to be, as a promise.
The first is that the word of the Law is “near in your hand.” This means that all the commandments have been clearly and thoroughly set forth for you.
You know and see them as one sees a thing held in the hand, or, as we say, in the palm. You have no need to soar upward or be carried far away in order to know them.
They are before your eyes. The second is that the word of these commandments is in the heart. This is a particular and chief moment in receiving the Law.
The Law written on tablets and parchment is near, so that the eye sees and the hand holds its letters. Yet it is still outside.
Its passage from outside into the heart is a special action or state in the one receiving the Law. In this state what is received outwardly enters within and is united with the whole being of man.
Then all the commandments are written in the heart. Such a state, or such a reception of the Law, was not the condition when the Law was given and received.
Nor was it then manifested. The Israelites were zealous for the Law out of gratitude and obedience to the mighty and beneficent God.
But the indication of what was lawful did not itself proceed from the heart. This was expected in the future. It was foreseen and indicated beforehand.
In the present passage there is only a hint of this. But afterward the Prophets set it forth more clearly when they foretold the New Covenant.
In it the laws would be written not on stone tablets, but on hearts. For this purpose the heart itself would be renewed, and a new spirit would be given to those entering that covenant (see Jer 31:33; Ezek 36:26).
Despite the hiddenness of the indication, however, this passage is not foreign to a predictive meaning. The same is true of the gathering from dispersion mentioned in passing just before (see Deut 30:4).
Therefore learned Jews did not err when they saw here an indication of the time of the coming of the promised Deliverer and Leader of the people.
For us, however, this Jewish understanding is not what is most precious. What is precious is that the apostolic spirit, the Spirit who brought forth these words of God, saw in them a pre-indication.
It was a pre-indication of what was fulfilled in its full meaning in Christ Jesus our Lord. Saint Paul refers this whole passage to the institution of the New Covenant.
He applies every term in those words of God to what is being accomplished in this covenant, as the realization of what was foretold.