The Greek does NOT supply a definite article ("the") in front of "law." So it should read "we establish A law." Now what law would a good antinomian like Paul be referring to? Of course, "the law of faith" - which he explicitly refers to here, just a few verses before...:
Ro 3:27 Where is boasting then? It is excluded. By what law? of works?
Nay: but by the law of faith.
So he does NOT "make void" the law, but rather "establishes" another law. Two laws exist simultaneously. How does that work? Well, we have an illustration...
The Medes and the Persians (Iranians) did not allow royal laws to be rescinded. If you made a law, it was for good. So it is with the divine law. If you wanted to OVERRIDE an inconvenient law, you had to pass a NEW law that SUPERCEDED the older law. Here is the example:
Da 6:15 Then these men assembled unto the king, and said unto the
king, Know, O king, that the law of the Medes and Persians is, That no
decree nor statute which the king establisheth may be changed. Da 6:17
And a stone was brought, and laid upon the mouth of the den; and the
king sealed it with his own signet, and with the signet of his lords;
that the purpose might not be changed concerning Daniel.
So when Namaan had a law made that would allow the Persians to kill the Jews, Mordecai had to write another law to allow them to defend themselves:
Esther 8:8 Write ye also for the Jews, as it liketh you, in the king’s
name, and seal it with the king’s ring: for the writing which is
written in the king’s name, and sealed with the king’s ring, may no
man reverse. ... 10 And he wrote in the king Ahasuerus’ name, and
sealed it with the king’s ring, and sent letters by posts on
horseback, and riders on mules, camels, and young dromedaries: 11
Wherein the king granted the Jews which were in every city to gather
themselves together, and to stand for their life, to destroy, to slay,
and to cause to perish, all the power of the people and province that
would assault them, both little ones and women, and to take the spoil
of them for a prey,
In this way the Jews triumphed over the plot against them.
So also the law (or, "principle") of faith does NOT in ANY WAY alter or destroy the law of Moses, BUT, it does OVERRIDE it.
Gal 3:15Brothers and sisters, let me take an example from everyday
life. Just as no one can set aside or add to a human covenant that has
been duly established, so it is in this case.
Rather than destroy a law, Paul says that faith is a new law that is established, that SUPERCEDES the law of Moses.
NIV Romans 8: 1Therefore, there is now no condemnation for those who
are in Christ Jesus, 2because through Christ Jesus the law [principle] of the
Spirit who gives life has set youa free from the law of sin and death.
All quotes from KJV unless otherwise noted.
I need to address another comment:
"Are you saying the faith of the Gentiles establishes a new law which gives righteousness different from that of Abraham?"
Paul uses "law" terminology loosely. What he's referring to is the "principle" of faith and "the terms" of justification.
Justification by faith is not a new thing. It is as old as Abel:
New American Standard Bible Hebrews 11:4 By faith Abel offered to God
a better sacrifice than Cain, through which he obtained the testimony
that he was righteous, God testifying about his gifts, and through
faith, though he is dead, he still speaks.
However, prior to the gospel there was no blanket opportunity for anyone to believe and be justified. One needed a divinely provided opportunity such as when God commanded Noah to build the ark.
With the advent of the gospel, Jew and gentile alike have a "healing serpent" lifted up to which anyone can look and live. This is the "law of faith" that Paul is saying is being established:
KJV Romans 3:
21But now the righteousness of God without the law is manifested, being witnessed by the law and the prophets; 22Even the righteousness
of God which is by faith of Jesus Christ unto all and upon all them
that believe: for there is no difference: 23For all have sinned, and
come short of the glory of God; 24Being justified freely by his grace
through the redemption that is in Christ Jesus: 25Whom God hath set
forth to be a propitiation through faith in his blood, to declare his
righteousness for the remission of sins that are past, through the
forbearance of God; 26To declare, I say, at this time his
righteousness: that he might be just, and the justifier of him which
believeth in Jesus.
27Where is boasting then? It is excluded. By what law? of works?
Nay: but by the law of faith. 28Therefore we conclude that a man is
justified by faith without the deeds of the law. 29Is he the God of
the Jews only? is he not also of the Gentiles? Yes, of the Gentiles
also: 30Seeing it is one God, which shall justify the circumcision by
faith, and uncircumcision through faith.
31Do we then make void the law through faith? God forbid: yea, we
establish the [actually, "a"] law.
The word translated "establish" is this:
ἵστημι (Hom.+, ins, pap [Mayser 353]; LXX [Thackeray 247f]; pseudepigr., Philo, Joseph., apolog. exc. Ar.) and also ἱστάνω (since I B.C. SIG 1104, 26 ἱστανόμενος; pap [Mayser, loc. cit., with ἀνθιστάνω documented here as early as III B.C.]; Epict. 3, 12, 2; LXX [Ezk 17:14; Thackeray, loc. cit.]; later wr. in Psaltes 236) Ro 3:31; Hs 8, 1, 10 (s. Whittaker on 8, 1, 8; s. B-D-F §93; Mlt-H. 202). Fut. στήσω; 1 aor. ἔστησα; 2 aor. ἔστην, impv. στῆθι, inf. στῆναι, ptc. στάς; pf. ἕστηκα (I stand), ptc. ἑστηκώς, ός and ἑστώς En 12:3; JosAs 7:2; J 12:29,-ῶσα J 8:9 v.l., neut. ἑστώς Rv 14:1 v.l. (s. B-D-F §96; W-S. §14, 5; Mlt-H. 222) and ἑστός, inf. always ἑστάναι; plpf. εἱστήκειν (I stood) or ἱστήκειν GPt 2:3, third pl. εἱστήκεισαν Mt 12:46; J 18:18; Ac 9:7; Rv 7:11 (W-H. spell it ἱστ. everywhere); ἑστάκαμεν w. act. mng. 1 Macc 11:34; fut. mid. στήσομαι Rv 18:15. Pass.: 1 fut. σταθήσομαι; 1 aor. ἐστάθην (PEg2 65). S. στήκω. Trans.: A. Intr.: B, C, D.
A. trans. (pres., impf., fut., 1 aor. act.; s. B-D-F §97, 1; Mlt-H. 241) gener. ‘put, place, set’.
① to cause to be in a place or position, set, place, bring, allow to come τινά someone, lit. ἐν τῷ συνεδρίῳ Ac 5:27. εἰς αὐτούς before them 22:30. ἐκ δεξιῶν τινος at someone’s right (hand) Mt 25:33. ἐν μέσῳ in the midst, among 18:2; Mk 9:36; J 8:3. ἐνώπιόν τινος before someone Ac 6:6. Also κατενώπιόν τινος Jd 24. ἐπί τι upon someth. Mt 4:5; Lk 4:9. παρά τινι beside someone 9:47.
② to propose someone for an obligation, put forward, propose, lit. (e.g. Just., A I, 60, 3 Μωυσέα … τύπον σταυροῦ … στῆσαι ἐπὶ τῇ ἁγίᾳ σκηνῇ) τινά for a certain purpose: the candidates for election to the apostleship Ac 1:23. μάρτυρας ψευδεῖς 6:13 (cp. Mel., P. 93, 700 ψευδομάρτυρες).
③ to set up or put into force, establish, fig. ext. of 1 (cp. Gen 26:3 τὸν ὅρκον; Ex 6:4) τὴν ἰδίαν δικαιοσύνην Ro 10:3. τὸ δεύτερον (opp. ἀναιρεῖν τὸ πρῶτον, a ref. to sacrificial system) Hb 10:9.—Of legal enforcement κύριε, μὴ στήσῃς αὐτοῖς ταύτην τ. ἁμαρτίαν Lord, do not hold this sin against them Ac 7:60 (contrast ἀφίημι 1 Macc 13:38f; 15:5; Stephen’s expression=ἄφες Lk 23:34; s. Beginn. IV, ad loc.).
④ to validate someth. that is in force or in practice, reinforce validity of, uphold, maintain, validate τὶ someth. fig. ext. of 1 (1 Macc 2:27 τὴν διαθήκην) τὴν παράδοσιν ὑμῶν validate or maintain your own tradition Mk 7:9. νόμον ἱστάνομεν we uphold (the) law Ro 3:31 (s. καταργέω 2).
⑤ to cause to be steadfast, make someone stand δυνατεῖ ὁ κύριος στῆσαι αὐτόν Ro 14:4.
⑥ to specify contractually
ⓐ set/fix a time a period of time ἡμέραν (s. ἡμέρα 3a) Ac 17:31.
ⓑ determine a monetary amount οἱ δὲ ἔστησαν αὐτῷ τριάκοντα ἀργύρια Mt 26:15 (=Zech 11:12 ἔστησαν τὸν μισθόν μου τριάκοντα ἀργύρους), presents a special problem for interpreters because of the author’s theological and narrative interests, which prompt him to connect an allusion here to Zech 11:12 in anticipation of a fulfillment statement at Mt 27:9f, which in haggadic fashion draws on Zech 11:13 in the longer form of the Mt and Jer 32 (Mt 39):7–9 (s. JDoeve, Jewish Hermeneutics in the Synoptic Gospels and Acts, ’54, 185–87). Jer 39:9 and Zech 11:12 use the verb ἱ. in the sense weigh out on scales (Hom.; X., Cyr. 8, 2, 21, Mem. 1, 1, 9 al.; GDI p. 870, n49 A [Ephesus VI B.C.] 40 minas ἐστάθησαν; Is 46:6; Jer 39:9; 2 Esdr 8:25), and some (e.g. BWeiss, HHoltzmann, JWeiss; FSchulthess, ZNW 21, 1922, 227f; Field, Notes 19f) interpret Mt 26:15 in this sense. Of course Mt’s readers would know that coinage of their time was not ‘weighed out’ and would understand ἱ. in the sense of striking a bargain (ἵστημι=set a price, make an offer, close a bargain: Herodas 7, 68 pair of shoes; BGU 1116, 8 [I B.C.]; 912, 25 [I A.D.]; PRainer 206, 10 [II A.D.] κεφάλαιον), they set out (=offered, allowed) for him (=paid him) 30 silver coins (Wlh., OHoltzmann, Schniewind), but the more sophisticated among them would readily recognize the obsolete mng. Ac 7:60 is sometimes interpreted in a related sense, but the absence of a direct object of amount paid suggests that the pass. is better placed in 3 above....
[intranstive and future forms omitted from citation - Ruminator]
Arndt, W., Danker, F. W., Bauer, W., & Gingrich, F. W. (2000). A Greek-English lexicon of the New Testament and other early Christian literature (3rd ed., pp. 482–483). Chicago: University of Chicago Press.