What causes confusion for some in this passage is its insistence that Jews keep every statute of the Law, which certainly was the case while that covenant was still in effect. But they take this time-connected requirement and conflate it with Jesus' statement that every single element of the Law must continue to remain meaningful until the end of the world.
Let's take a look at these 2 ideas, and distinguish them so that they are not conflated, confusing the meaning. One, there is no question that the Law was a covenant. The covenant had been established with Abraham, Isaac, and Jacob well before the Law was given. But when the nation had grown into a nation, they were taken to Sinai where this covenant was squarely built upon the Law.
In the NT Scriptures it is argued by Paul that the Law and the Promises are distinct, because one is conditional, subject to failure, while the other is eternal and unconditional. This means that the covenant, which can be broken, can fail, whereas the promises were conditioned on God's fidelity and can never fail.
How can this be resolved? It is stated, as a matter of fact, that the Law was never intended to be successful over the long haul. From a simple reading of the last part of Deuteronomy it can be understood that God anticipated the failure of national Israel in the end and throughout their history. This was a conditional covenant that would fail!
The Promises, on the other hand, gave hope to Israel in the midst of this fatalistic covenant, because they were assured that God's word can never fail and that somehow Israel would succeed despite their inevitable failure under the covenant.
So let's return to what Jesus said. He indicated, while Israel was still under this covenant, that they should remain completely devoted to it in the hope that God would somehow enable them to prevail regardless of the inevitable failure. And he indicated that though the Law would fail and result in his own death and in Israel's ultimate exile that every aspect of the Law would be fulfilled, both its own demise and the very hope it tried to bring for Israel's future.
That means that every element of the Law could not be sacrificed so as to preserve this testimony. It was just as the book of Revelation indicated--do not mess with the words of this prophecy. Do not take away anything that is said, and do not add anything that is not there.
Both elements had to be preserved in the full testimony of the Law--every jot and tittle (characters that gave meaning to Israel's alphabet). It was the *meaning* of the Law that had to be preserved, and not its covenant continuity. It was its *message* that had to be preserved, which would be secured by strict adherence to it while it was in effect.
Strict adherence to the Law meant both things, that Israel had to prevail in righteousness and that it would prevail only by God's mercy. The entire Law was predicated on God's mercy, because even the most righteousness they could produce was insufficient if they did not provide animal offerings and sacrifices, along with purification cermonies, and recognition of the need for human conformity to God's rules of redemption. Redemption implied the need for mercy, and that human works were insufficient for Salvation.
This is the testimony that Israel's compliance to the Law hoped to state--the need for both righteousness and mercy, and not the need to preserve the covenant itself. In Jer 31.31 it became clear that Israel's failure was tantamount to the inability of the covenant of Sinai to prevail over the long run. Salvation would come by a new covenant, based on mercy.
So what exactly is it that renders the Law meaningful, in every element, until the end of the world? It is the ultimate failure of Israel to be justified by an obsolete Law, as well as the judgment against all men that they must die and must somehow be saved by the righteousness of Christ. This is what Jesus was implying, though he was doing it while the Law remained in effect. I wish I could be clearer about this!
