Dr. Thomas Ice
And those who will walk by this rule, peace and mercy be upon them, and upon the Israel of God.
A while back I was talking to a friend of mine about the modern state of Israel. This friend, born and raise in Damascus, Syria, is a Muslim. He is a well-educated man, who has lived in our country for about 40 years. As our conversation developed, I was taken back when he told me that the Jewish people of today had no claim to the land of Israel because the church has replaced Israel. He then cited Galatians 6:16. I was amazed that a Muslim has such a grasp of the Christian false teaching called replacement theology. It is not surprising to hear this from certain segments of Christendom, but to realize that this errant viewpoint had penetrated into the American Muslim community was amazing to me.
Preterist and covenant theologian, Kenneth Gentry defines replacement theology- to which he holds- as follows: "We believe that the international Church has superseded for all times national Israel as the institution for the administration of divine blessing to the world."  Gentry uses supersession as a synonym for replacement. I could almost agree with his definition if he would remove the phrase "all times." We dispensationalists believe that the church has superseded Israel during the current church age, but God has a future time in which He will restore national Israel "as the institution for the administration of divine blessing to the world.
Gentry adds to his initial statement the following embellishment:
That is, we believe that in the unfolding of the plan of God in history, the Christian Church is the very fruition of the redemptive purpose of God. As such, the multi-racial, international Church of Jesus Christ supersedes racial, national Israel as the focus of the kingdom of God. Indeed, we believe that the Church becomes "the Israel of God" (Gal. 6:16), the "seed of Abraham" (Gal. 3:29), "the circumcision" (Phil. 3:3), the "temple of God" (Eph. 2:19-22), and so forth. We believe that Jew and Gentile are eternally merged into a "new man" in the Church of Jesus Christ (Eph. 2:12- 18). What God hath joined together let no man put asunder!
Randall Price provides an excellent and comprehensive definition:
Replacement Theology: a theological perspective that teaches that the Jews have been rejected by God and are no longer God’s Chosen People. Those who hold to this view disavow any ethnic future for the Jewish people in connection with the biblical covenants, believing that their spiritual destiny is either to perish or become a part of the new religion that superseded Judaism (whether Christianity or Islam).
Perhaps the last definition provides some insight into what an American Muslim and American Christian have in common. They both believe that Israel is permanently replaced by the church and that the church is the Israel of God from Galatians 6:16.
Gentry believes that Galatians 6:16 teaches that the church has replaced or superseded Israel.
If Abraham can have Gentiles as his "spiritual seed," why cannot there be a spiritual Israel? In fact, Christians are called by the name "Israel" : "And as many as walk according to this rule, peace and mercy by upon them, and upon the Israel of God" (Gal. 6:16).
The is such a thing as "spiritual Israel." Spiritual Israel would refer to Jewish people who have trusted Jesus as their Messiah; but the church is never called "spiritual Israel," as Gentry claims. Let’s look at Galatians 6:16 and see what it actually says.
The passage is simple and clear. The first part of verse 16, which says, "those who walk by this rule;" refers to the rule Paul had just stated in verse 15. "For neither is circumcision anything, nor uncircumcision, but a new creation." This is a spiritual category referring to all believers, to which Paul pronounces a blessing: "peace and mercy be upon them." This is followed by his copulative comment "and upon the Israel of God."
S. Lewis Johnson surveys the different suggestions in Galatians 6:16 for translating the Greek word kai, which is normally translated "and." Johnson says, "in absence of compelling exegetical and theological considerations, we should avoid the rarer grammatical usages when the common ones make good sense."  He demonstrates that they is no exegetical or theological reason to not take "and" in its normal sense in this passage. Johnson concludes,
if it were Paul’s intention to identify the "them" of the text as "the Israel of God," then why not simply eliminate the kai after "mercy?" The result would be far more to the point, if Paul were identifying the "them," that is, the church, with the term "Israel." The verse would be rendered then, "And as many as shall walk by this rule, peace be upon them and mercy, upon the Israel of God." A case could be solidly made for the apposition of "the Israel of God" with "them," and the rendering of the NIV could stand. Paul, however, did not eliminate the kai.
Johnson is saying that there is no textual or exegetical basis for Gentry’s belief that Galatians 6:16 teaches that the "Israel of God" includes the church or Gentiles. Gentry’s replacement theology or supersesionism- as he likes to call it- has no basis in the biblical text. It must be that he is so blinded by the demands of his false theology that he continues to insist upon such an interpretation of the Bible and his resulting errant theology. I wonder, along with Lewis Johnson, why "In spite of overwhelming evidence to the contrary, there remains persistent support for the contention that the term Israel may refer properly to Gentile believers in the present age." 
E. D. Burton says, "In view of the apostle’s previous strong anti-judaistic expressions, he feels impelled, by the insertion of and, to emphasize this expression of his true attitude towards his people."  Hebrew Christian scholar, Arnold Fruchtenbaum summaries the passage as follows:
Galatians is concerned with Gentiles who were attempting to attain salvation through the Law. The ones deceiving them were the Judaizers, who were Jews demanding adherence to the Law of Moses. To them, a Gentile first had to convert to Judaism before he was qualified for salvation through Christ. In verse fifteen Paul states that the important thing for salvation is faith, resulting in the new man. He then pronounces a blessing on two groups who would follow this rule of salvation by faith alone. The first group is the them, the Gentile Christians to and of whom he had devoted most of the epistle. The second group is the Israel of God. These are Hebrew Christians who, in contrast with the Judaizers, followed the rule of salvation by faith alone. Again a distinction between the two groups is seen, for the Hebrew Christians alone are the Israel of God. It is a matter of position which here acts out a definite function.
A number of years ago, I was discussing biblical prophecy with a person who was writing articles in a magazine from a replacement theology perspective. I kept hammering away at him with the slogan "Israel always means Israel," as he would replace Israel with the church in Old Testament passage after passage. Finally he complained to me something along the lines of "You keep bringing in your theological presupposition that ' Israel always means Israel.' "I replied that this was not a theological a priori, instead it was an exegetical conclusion; and so it is.
In fact, there is not a single instance in the entire Bible where Israel refers to anything other than the Jewish people. Burton declares,
there is, in fact, no instance of his [Paul] using Israel except of the Jewish nation or a part thereof. These facts favour the interpretation of the expression as applying not to the Christian community, but to Jews; yet, in view of "of God," not to the whole Jewish nation, but to the pious Israel, the remnant according to the election of grace (Rom. 11:5).
Lewis Johnson is equally insistent when he says,
There is no instance in biblical literature of the term Israel being used in the sense of the church, or the people of God composed of both believing ethnic Jews and Gentiles. Nor, on the other hand, as one might expect if there were such usage, does the phrase ta ethn (KJV, "the Gentiles" ) ever mean the non-Christian world specifically, but only the non-Jewish peoples, although such are generally non-Christians.
Fruchtenbaum summaries the distinction between Israel and the church as follows:
The first evidence is the fact that the church was born at Pentecost, whereas Israel had existed for many centuries. . . .
The second evidence is that certain events in the ministry of the Messiah were essential to the establishment of the church- the church does not come into being until certain events have taken place. . . .
The third evidence is the mystery character of the church. . . .
The fourth evidence that the church is distinct from Israel is the unique relationship between Jews and the Gentiles, called one new man in Ephesians 2:15. . . .
The fifth evidence for the distinction between Israel and the church is found in Galatians 6:16. . . .
Perhaps one more observation can be made. In the book of Acts, both Israel and the church exist simultaneously. The term Israel is used twenty times and ekklesia (church) nineteen times, yet the two groups are always kept distinct.
It is not just a theological belief that "Israel always means Israel," and that Israel and the church are distinct peoples of God. These things are specifically taught in the Bible. We are currently living in the church age, which will end with the any-moment rapture when the last person is saved into the body of Christ. Then, the history will complete the final week of Daniel’s seventy-week prophecy, which will end with Israel’s conversion to Jesus as their Messiah. This will lead to the thousand-year kingdom in which Israel will be the head over all the nations. Not only does the Bible distinguish between God’s plan for Israel and His plan for the church, but it also teaches a distinction between saved and lost Jewish people in Galatians 6:16. This is one of the things denied by replacement theology. C. E. B. Canfield has said the following concerning this matter.
It is only where the Church persists in refusing to learn this message, where it secretly- perhaps quite unconsciously!- believes that its own existence is based on human achievement, and so fails to understand God’s mercy to itself, that it is unable to believe in God’s mercy for still unbelieving Israel, and so entertains the ugly and unscriptural notion that God has cast off His people Israel and simply replaced it by the Christian Church. These three chapters [Romans 9–11] emphatically forbid us to speak of the Church as having once and for all taken the place of the Jewish people. . . . But the assumption that the Church has simply replaced Israel as the people of God is extremely common. . . . And I confess with shame to having also myself used in print on more than one occasion this language of the replacement of Israel by the Church.
 Kenneth L. Gentry, Jr., "Supersessional Orthodoxy; Zionistic Sadism," Dispensationalism in Transition, Vol. VI, No. 2; Feb. 1993, p. 1.
 Kenneth L. Gentry, Jr., "The Iceman Cometh! Moronism Reigneth!," Dispensationalism in Transition, Vol. VI, No. 1; Jan. 1993, p. 1.
 Randall Price, Unholy War: America, Israel and Radical Islam (Eugene, OR: Harvest House, 2001), p. 412.
 Kenneth L. Gentry, Jr., He Shall Have Dominion: A Postmillennial Eschatology (Tyler, Tex.: Institute for Christian Economics, 1992), p. 167.
 S. Lewis Johnson, Jr., "Paul and ' The Israel of God' : An Exegetical and Eschatological Case-Study," in Stanley D. Toussaint & Charles H. Dyer, Essays in Honor of J. Dwight Pentecost (Chicago: Moody Press, 1986), p. 187.
 Johnson, "The Israel of God," p. 188.
 Johnson, "The Israel of God," p. 181.
 Ernest De Witt Burton, A Critical and Exegetical Commentary on The Epistle to The Galatians, (Edinburgh: T & T Clark, 1920), p. 358.
 Arnold G. Fruchtenbaum, Hebrew Christianity: Its Theology, History, and Philosophy (Washington, DC: Canon Press, 1974), p. 33.
 Burton, Galatians, p. 358.
 Johnson, "The Israel of God," p. 189.
 Arnold G. Fruchtenbaum, "Israel and the Church," in Wesley R. Willis and John R. Master, Gen. Editors, Issues In Dispensationalism (Chicago: Moody Press, 1994), pp. 116- 118.
 C. E. B. Cranfield, A Critical and Exegetical Commentary on The Epistle to The Romans, 2 vols. (Edinburgh: T & T Clark, 1979), vol. 2, p. 448.