17 Behold, thou art called a Jew, and restest in the law, and makest thy boast of God,
1901 ASV Translation:
17 But if thou bearest the name of a Jew, and restest upon the law, and gloriest in God,
In verse 17, the Textus Receptus has the equivalent of "Behold" and the Nestle/Aland 26 has, instead, "But if". The difference is that the Nestle/Aland 26 has the Greek letter epsilon in the text before the iota that is in both texts. That extra letter, plus a different way of dividing the lettering, creates this difference.
I. With 2:17 the apostle begins to take on the self-righteousness (see 10:3) of what he calls "a Jew".
A. In view of 3:9, we know that it is his intent to demonstrate the "under sin" condition of all men except those who belong to Christ.
B. Given this intent, and given the propensity of the "Jew" toward self-righteousness, Paul determines to first address the "self-concept" that was prevalent among those he designates as "Jews".
II. The Second Issue of the Verse: "Resting".
A. Paul says of the one calling himself "Jew" that he "rests in/upon the Law".
B. The word is used only twice in the New Testament, but only because it is another compound word that puts together more than one concept. In general, the word means "to cease from labor because of a provision being made that no longer requires such labor".
C. For the self-proclaimed "Jew", there was "rest" in a certain perception of "Law".
1. This "perception" was that "Law" was given by God to make it possible for those who would obey it to escape from His wrath.
2. Thus, the "rest" was in view of the difficult labor that attends those who are in straits because they are under the condemnation of the Final Judge. To discover a "way out from under that condemnation" was to find "rest". Who would not heave a great sigh of relief to discover the unguarded and unlocked door of a terrible prison?
3. So we can conclude that the "rest" was not "physical", but something that attends the "soul" when the fears that plagued it are dismissed. Jesus meant something of this sort when He promised "rest unto your souls" (Matthew 11:29).
4. Given the way Paul is going to develop his argument, it is a shock to discover that there are folks who are "resting" in the very Law that is going to be the implacable cause of their destruction...as they "store up wrath for themselves in the day of wrath" (2:5). The "rest" is based on delusion and, though it has been genuinely developed in the soul so that the soul is no longer plagued with scenes of awful destruction, it will, in the Day of the Revelation of the Righteous Judgment of God, be revealed to have been a false "rest" indeed. It is an opiate that falsely describes reality so that delusional "rest" can pervade the soul and squelch the motivation to find peace with the Judge.
5. Given, also, the terrible meticulousness of "legalism" as it had been developed by the first century in Israel, it is hard to imagine anyone calling the pursuit of that intricate web of performance "rest"...but such was the blindness which Paul saw so clearly after he had, himself, been delivered from the deceit.
III. Boasting in God...Paul's third characterization of the self-proclaimed "Jew".
A. The word "boasting" means "to both experience, and to tell of, a great exulting in the spirit" because of some fantastic priviledge given.
B. For the self-proclaimed "Jew", having the "true" God as one's God was a matter of enormous exulting in the spirit. There is nothing quite like being "right" about an issue as critical as identifying, and owning, the true God.