by Michael Marlowe, Dec. 2004 :
"The proper interpretation and translation of the last phrase in Galatians 6:16 has become a matter of controversy in the past century or so. Formerly it was not a matter of controversy. With few exceptions, "The Israel of God" was understood as a name for the Church here.  The καὶ ("and") which precedes the phrase ἐπὶ τὸν Ἰσραὴλ τοῦ θεοῦ ("upon the Israel of God") was understood as an explicative καὶ. This understanding of the grammar is reflected in the Revised Standard Version's "Peace and mercy be upon all who walk by this rule, upon the Israel of God," and in the New International Version's "even to the Israel of God." It is not necessary, however, to understand the καὶ as an explicative in order to get substantially the same sense. If it be regarded as an ordinary connective καὶ, as Marvin Vicent says, "The ὅσοι ['as many as'] will refer to the individual Christians, Jewish and Gentile, and Israel of God to the same Christians, regarded collectively, and forming the true messianic community." (Word Studies in the New Testament vol. 4, p. 180). So the rendering "and upon the Israel of God" (KJV and others) is acceptable enough, if it is not misunderstood. In any case, it seems clear that in this verse Paul cannot be pronouncing a benediction upon persons who are not included in the phrase "as many as shall walk by this rule" (the rule of boasting only in the cross). The entire argument of the epistle prevents any idea that here in 6:16 he would give a blessing to those who are not included in this group.
The phrase has become controversial because the traditional interpretation conflicts with principles of interpretation associated with Dispensationalism. Dispensationalists are interested in maintaining a sharp distinction between "Israel" and "the Church" across a whole range of theological matters pertaining to prophecy, ecclesiology, and soteriology. They are not comfortable with the idea that here Paul is using the phrase "Israel of God" in a sense that includes Gentiles, because this undermines their contention that "the Church" is always carefully distinguished from "Israel" in Scripture. This is a major tenet of dispensationalist hermeneutics. C.I. Scofield in his tract, Rightly Dividing the Word of Truth (New York, Loizeaux Brothers, 1888) wrote, "Comparing, then, what is said in Scripture concerning Israel and the Church, [a careful Bible student ] finds that in origin, calling, promise, worship, principles of conduct, and future destiny--all is contrast." Likewise Charles Ryrie in his book Dispensationalism Today (Chicago, 1965) explained that the "basic premise of Dispensationalism is two purposes of God expressed in the formation of two peoples who maintain their distinction throughout eternity." (pp. 44-45).
The traditional Protestant and Catholic approach to this matter is quite different, however, because in these traditions "Israel" is often interpreted typologically. The Church is understood to be a "Spiritual Israel," so that many things said in connection with Israel in Scripture are applied to the Church. For instance, the words of Psalm 122, "Pray for the peace of Jerusalem: they shall prosper that love thee," are understood as in Matthew Henry's commentary: "The peace and welfare of the gospel church ... is to be earnestly desired and prayed for." This is in keeping with the method of the apostles, as for instance in Galatians 4:26, where the apostle Paul speaks of "the Jerusalem that is above." Therefore when Paul speaks of "the Israel of God" in 6:16, the meaning of this expression is readily grasped. Rather than seeing a contrast, a deeply meaningful typological relationship is perceived.
As a young Christian I attended a church where the Dispensationalist approach was taught, and I remember how it was frequently supported by the statement that in Scripture "the Church is never called Israel." Galatians 6:16 was explained as if the phrase "and upon the Israel of God" referred to a Jewish subset of those people who "walk by this rule," that is, the Christians of Jewish ethnic background as distinguished from those who are of non-Jewish background. Apparently this unqualified assertion that the Church is never spoken of as "Israel" continues to be important to dispensationalists, because in a recent article a prominent dispensationalist author calls it a "horrendous mistake" when "the Israel of God" in Galatians 6:16 is understood to include Gentiles.  There does not seem to be any reason for this interpretation aside from the desire of dispensationalists to exclude all typological interpretations and to defend their contention that "the Church is never called Israel."
Aside from typological considerations, this dispensationalist explanation of the meaning of "The Israel of God" in Galatians 6:16 seems contrary to the tenor of the epistle, in which it is said that "in Christ Jesus ... there is neither Jew nor Greek." This is the central idea of the epistle, as expressed in the third chapter: "you are all one in Christ Jesus ... if you are Christ's, then you are Abraham's offspring" (3:26-29). Scofield himself acknowledged this when he wrote, "In the Church the distinction of Jew and Gentile disappears." This raises several questions. If "in the Church the distinction of Jew and Gentile disappears," as Scofield says, then why would Paul make such a distinction in 6:16? And if it is true that the Church is never called Israel in Scripture, and "all is contrast" between the two, then in what sense can Christians of Jewish background be called "Israel" any longer, if they are in the Church? If someone in the Church is being called "Israel," then the all-important distinction between Israel and the Church has been breached. If it is said that people of Jewish background may still be called "Israel" after they have become Christians, then it must be admitted that the strict terminological distinction between "Israel" and "the Church" has broken down at this point. Further, if it is said that only persons of Jewish backgound can be so called, then we may rightly ask what has become of the teaching that "In the Church the distinction of Jew and Gentile disappears"? Do we have a separate class of "Jewish Christians" who alone are entitled to the name "Israel of God"? If so, what is the significance of this? Are there two types of Christianity, two Churches? My own experience of dispensationalist teaching suggests to me that in fact this is the view held by many dispensationalists today: the idea is that there is a "Jewish" Christianity and a "Gentile" Christianity, and in some sense the "Jewish" Christians are thought to be more important and especially favored by God. 
The older dispensationalist writers, such as Darby, Scofield, and Chafer, avoided some of these embarrassing questions and implications because their distinction between Israel and the Church was more consistent and more radical. Scofield believed that the Jews of the end times were to be saved according to the Law of Moses, with renewed animal sacrifices. His scheme of interpretation envisioned a time when the parenthetical "Church age" has ended and the Law of Moses is reinstituted for salvific purposes. After this change of "dispensations" people will be saved according to a different gospel, the "Gospel of the Kingdom." Paul's doctrine (called the "Gospel of the Grace of God") was no longer in effect. Paul's teaching on the unity of the Church did not apply because the Church has been "raptured" and is no longer in the earth, and God is no longer dealing with the Church. In this manner the distinction between "Israel" and "the Church" was upheld without denying the unity of the body of Christ. But it is difficult to speak of Scofield's "Israel" of the end-times as consisting of "Jewish Christians," because they are not in the Church, and they are not dealt with on the same terms as the Christians who are of the Church. They are "God's earthly people," according to Scofield, as distinguished from the Church, who are God's "heavenly people." They are the "wife of Jehovah" and not the "bride of Christ," and so forth. Such teachings of the classic dispensationalist theology rigorously maintained the distinction between "Israel" and "the Church." If this distinction is to be upheld in Galatians 6:16 then presumably the "Israel of God" must be taken as a reference to the eschatological Israel who are to be saved by a different gospel, after Paul's own gospel dispensation has ended.  But one rarely hears this kind of pure and radical dispensationalist teaching now. Today dispensationalists seem to be in a muddle, having moved away from consistency in distinguishing Israel and the Church. Israel may now be spoken of as a part of the Church, and so there is a special and privileged class of "Jewish Christians" within the body of Christ. 
These features of dispensationalism raise many serious theological problems which I will not go into here. My main purpose here has been to show what notions are being brought to the text when a dispensationalist says it is a "horrendous mistake" to interpret Paul's "Israel of God" as a way of referring to the Church in Galatians 6:16. The dispensationalist complaint against the traditional understanding of Galatians 6:16 is, in my opinion, an example of sectarian "end-times prophecy" baggage being brought to the text, and it does not represent a serious attempt to understand the phrase in its context.
Other agendas are at work among non-dispensationalist scholars who have argued against the traditional view. When I was a seminary student in the early 1990's one liberal professor's favorite topic was "anti-semitism" in the Church, and he was an outspoken opponent of evangelization of the Jews. This professor taught a course on the Pauline epistles in which he objected to the traditional interpretation on the grounds that it was anti-semitic. He maintained that in Galatians 6:16b Paul was blessing the nation of Israel, not appropriating the name "Israel" for the Church, nor even using the phrase "Israel of God" for Christians of Jewish background. In his opinion, Paul's statement should be read as an affirmation of the kind of religious pluralism that prevails in liberal circles. I am not aware of an exegetical commentary which adopts this very dubious view, but the HarperCollins Study Bible (1993) prepared by liberal scholars does have a note at Galatians 6:16 which reads, "Israel of God, the church as the true Israel ... or, alternately, the whole people of Israel." Although the annotator of Galatians here (indentified as Richard B. Hays of Duke University in the list of contributors) goes on to say "the argument of Galatians appears to support the former interpretation," the alternative he gives is not "Jewish Christians" but "the whole people of Israel." The pluralism and the opposition to Jewish evangelism I encountered at Pittsburgh Theological Seminary is probably one reason for this, and also one reason why the New Revised Standard Version (1989) revisers inserted the word "and" before the RSV's "upon the Israel of God." Here again a good deal of baggage is being brought to the text, consisting of ideas which are completely foreign to Paul's gospel.
It may be wondered whether some dispensationalists have also adopted the view that "the Israel of God" simply refers to Israel according to the flesh. As noted above, it would be entirely in keeping with the earlier dispensationalist writers to maintain that Paul is blessing Jews who are outside of the Church, as the "earthly people of God." The fascination with the secular state of Israel which is so characteristic of dispensationalists today has apparently led many of them to think that the restoration of the Jews as "God's people" has already occured, despite the fact that the Church has not been raptured and the Jews continue to reject Christ. Dispensationalists insist that this unbelieving Israel according to the flesh must be blessed by everyone. If this is the case, why indeed should Paul not be blessing them as the "Israel of God" in Galatians 6:16? But of course the premise is all wrong, because there is no blessing for those who reject Christ.
In conclusion, I will state my opinion that the attempt to limit the meaning of "Israel of God" to the carnal sons of Judah betrays a fundamentally wrong approach to biblical interpretation, and to New Testament theology in particular. I give below some excerpts from writers whom I believe to be more in touch with the meaning of Paul's expression. Even in these authors I find, however, an insufficient appreciation of Paul's expression. "Peace be ... upon the Israel of God" is not so much a polemical or ironic usage directed against the Judaizers (Luther and Calvin) as a positive blessing and affirmation of the Church as the true spiritual Israel. It is a mistake to see bitterness in this blessing.
Justin Martyr on "the true spiritual Israel" 
Jesus Christ ... is the new law, and the new covenant, and the expectation of those who out of every people wait for the good things of God. For the true spiritual Israel, and the descendants of Judah, Jacob, Isaac, and Abraham (who in uncircumcision was approved of and blessed by God on account of his faith, and called the father of many nations), are we who have been led to God through this crucified Christ.
John Chrysostom on Galatians 6:15-16 
Observe the power of the Cross, to what a pitch it hath raised him! not only hath it put to death for him all mundane affairs, but hath set him far above the Old Dispensation. What can be comparable to this power? for the Cross hath persuaded him, who was willing to be slain and to slay others for the sake of circumcision, to leave it on a level with uncircumcision, and to seek for things strange and marvellous and above the heavens. This our rule of life he calls "a new creature," both on account of what is past, and of what is to come; of what is past, because our soul, which had grown old with the oldness of sin, hath been all at once renewed by baptism, as if it had been created again. Wherefore we require a new and heavenly rule of life. And of things to come, because both the heaven and the earth, and all the creation, shall with our bodies be translated into incorruption. Tell me not then, he says, of circumcision, which now availeth nothing; (for how shall it appear, when all things have undergone such a change?) but seek the new things of grace. For they who pursue these things shall enjoy peace and amity, and may properly be called by the name of "Israel." While they who hold contrary sentiments, although they be descended from him and bear his appellation, have yet fallen away from all these things, both the relationship and the name itself. But it is in their power to be true Israelites, who keep this rule, who desist from the old ways, and follow after grace.
Martin Luther on Galatians 6:16
Lectures on Galatians, 1519. "Walk" is the same verb that is used above (5:25). "Walk," that is, go, by this rule. By what rule? It is this rule, that they are new creatures in Christ, that they shine with the true righteousness and holiness which come from faith, and that they do not deceive themselves and others with the hypocritical righteousness and holiness which come from the Law. Upon the latter there will be wrath and tribulation, and upon the former will rest peace and mercy. Paul adds the words "upon the Israel of God." He distinguishes this Israel from the Israel after the flesh, just as in 1 Cor. 10:18 he speaks of those who are the Israel of the flesh, not the Israel of God. Therefore peace is upon Gentiles and Jews, provided that they go by the rule of faith and the Spirit.
Lectures on Galatians, 1535. "Upon the Israel of God." Here Paul attacks the false apostles and the Jews, who boasted about their fathers, their election, the Law, etc. (Rom. 9:4-5). It is as though he were saying: "The Israel of God are not the physical descendants of Abraham, Isaac, and Israel but those who, with Abraham the believer (3:9), believe in the promises of God now disclosed in Christ, whether they are Jews or Gentiles."
John Calvin on Galatians 6:16 
Upon the Israel of God. This is an indirect ridicule of the vain boasting of the false apostles, who vaunted of being the descendants of Abraham according to the flesh. There are two classes who bear this name, a pretended Israel, which appears to be so in the sight of men, and the Israel of God. Circumcision was a disguise before men, but regeneration is a truth before God. In a word, he gives the appellation of the Israel of God to those whom he formerly denominated the children of Abraham by faith (Galatians 3:29), and thus includes all believers, whether Jews or Gentiles, who were united into one church.
William Hendriksen on Galatians 6:16 
Paul continues: 16. And as many as shall walk by this rule, peace (be) upon them and mercy, even upon the Israel of God. According to the preceding context, this rule is the one by which before God only this is of consequence, that a person places his complete trust in Christ crucified, and that, therefore, he regulates his life by this principle. This will mean that his life will be one of gratitude and Christian service out of love for his wonderful Savior. Upon those — all those and only those — who are governed by this rule peace and mercy are pronounced. Peace is the serenity of heart that is the portion of all those who have been justified by faith (Rom. 5:1). In the midst of the storms of life they are safe because they have found shelter in the cleft of the rock. In the day of wrath, wasteness, and desolation God "hides" all those who take refuge in him (Zeph. 1:2 ff.; 2:3; 3:12). See on 1:3. Hence, peace is spiritual wholeness and prosperity. Peace and mercy are inseparable. Had not the mercy of God been shown to his people they would not have enjoyed peace. God's mercy is his love directed toward sinners viewed in their wretchedness and need. See N.T.C. on Philippians, p. 142, for a list of over one hundred Old and New Testament passages in which this divine attribute is described.
So far the interpretation runs smoothly. A difficulty arises because of the last phrase of this verse. That last phrase is: "kai upon the Israel of God." Now, varying with the specific context in which this conjunction kai occurs, it can be rendered: and, and so, also, likewise, even, nevertheless, and yet, but, etc. Sometimes it is best left untranslated. Now when this conjunction is rendered and (as in A.V., A.R.V., N.E.B.), it yields this result, that after having pronounced God's blessing upon all those who place their trust exclusively in Christ Crucified, the apostle pronounces an additional blessing upon "the Israel of God," which is then interpreted to mean "the Jews," or "all such Jews as would in the future be converted to Christ," etc.
Now this interpretation tends to make Paul contradict his whole line of reasoning in this epistle. Over against the Judaizers' perversion of the gospel he has emphasized the fact that "the blessing of Abraham" now rests upon all those, and only those, "who are of faith" (3:9); that all those, and only those, "who belong to Christ" are "heirs according to the promise" (3:29). These are the very people who "walk by the Spirit" (5:16), and "are led by the Spirit" (5:18). Moreover, to make his meaning very clear, the apostle has even called special attention to the fact that God bestows his blessings on all true believers, regardless of nationality, race, social position, or sex: "There can be neither Jew nor Greek; there can be neither slave nor freeman; there can be no male and female; for you are all one in Christ Jesus" (3:28). By means of an allegory (4:21-31) he has re-emphasized this truth. And would he now, at the very close of the letter, undo all this by first of all pronouncing a blessing on "as many as" (or: "all") who walk by the rule of glorying in the cross, be they Jew or Gentile by birth, and then pronouncing a blessing upon those who do not (or: do not yet) walk by that rule? I refuse to accept that explanation. Appeals to the well-known "Eighteen petition prayer of the Jews,"  to the meaning of the word Israel in other New Testament passages, etc., cannot rescue this interpretation. As to the former, Gal. 6:16 must be interpreted in accordance with its own specific context and in the light of the entire argument of this particular epistle. And as to the latter, it is very clear that in his epistles the apostle employs the term Israel in more than one sense. In fact, in the small compass of a single verse (Rom. 9:6) he uses it in two different senses. Each passage in which that term occurs must therefore be explained in the light of its context. Besides, Paul uses the term "the Israel of God" only in the present passage, nowhere else.
What, then, is the solution? In harmony with all of Paul's teaching in this epistle (and see aslo Eph. 2:14-22), and also in harmony with the broad, all-inclusive statement at the beginning of the present passage, where the apostle pronounces God's blessing of peace and mercy upon "as many as" shall walk by this rule, an object from which nothing can be subtracted and to which nothing can be added, it is my firm belief that those many translators and interpreters are right who have decided that kai, as here used, must be rendered even, or (with equal effect) must be left untranslated. Hence, what the apostle says is this: "And as many as shall walk by this rule, peace (be) upon them and mercy, even upon the Israel of God." Cf. Psalm 125:5. Upon all of God's true Israel, Jew or Gentile, all who truly glory in the cross, the blessing is pronounced.
O. Palmer Robertson on the Israel of God 
The recognition of a distinctive people who are the recipients of God’s redemptive blessings and yet who have a separate existence apart from the church of Jesus Christ creates insuperable theological problems. Jesus Christ has only one body and only one bride, one people that he claims as his own, which is the true Israel of God. This one people is made up of Jews and Gentiles who believe that Jesus is the promised Messiah."