This change shall occur because of a subterranean spiritual deterioration within Evangelicalism, which is now undeniable in light of the 2016 Republican Primaries and the Trump phenomenon. This change shall occur because the stream of Evangelicalism most favorable to the Jews, namely Dispensationalism, is declining in credibility and influence, relative to their “supersessionist” counterparts. This change shall occur because the political needs and actions of the American Diasporic Jew tend to work against Evangelical interests, even to the point of now threatening the latter’s socioeconomic welfare. This change shall occur because the prevailing cultural notions within the over-sized influence of American Jewry is contrary to the cultural heritage of the host country.
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Evangelical support of the Jews, as a broad and recognizable movement, originates with the Dispensationalists (Plymouth Brethren) in the 1820s and 30s, who subscribed to the notion, based on Scriptures, of a physical restoration of the state of Israel. This “far-fetched” belief well preceded the First Zionist Congress (1897) and establishment of the State of Israel (1948). In its fulfillment and later expansion into Old Jerusalem with the Six Days War (1967), Dispensationalism (and all of its accompanying baggage, including “Left Behind” eschatology) became a rising star in the 1970s.
Jews, although appreciative of their support, largely disdain these Evangelical Judeophiles as “useful idiots.” If this Jewish attitude is recognized at all by Evangelicals, it has not been of grave concern since they believe that God is about to perform a great spiritual revival within Israel and the Jewish community despite of themselves. Such Evangelicals wish to be the conduit through which this occurs; or, at least, not be a stumbling block to this eventuality.
But these last decades have witnessed a decline in spiritual vitality, faith commitment, biblical literacy, theological understanding, and orthodoxy since Evangelicalism’s 1970s and 1980s heydays, as evidenced by a bounty of sociological surveys, ecclesiastical statistics (e.g. declining memberships and baptisms, and “fleeing of the Millennials”), various commentators, and now voting patterns. Without a Scriptural (eschatological) basis, and a diminishing population of true Evangelicals, support for the Israeli state and Jewish people will likewise decline.
Furthermore, while much of Evangelicalism languishes in pietistic incoherence, the thriving, more intelligent and intelligible segments of Evangelicalism (e.g. New Calvinists) tend towards a Postmillennialism or Amillennialism eschatology, denigrating any special status or significance to the restoration of physical Israel, and committed to Replacement Theology (Supersessionism) in all but name. Indeed, one can detect an undercurrent of offhandedness, if not mild hostility, towards the Jews.
The decline of Dispensationalism and rise of Calvinistic Christianity owes much to the relative rational incoherence of the former stream’s theology; the “Free Grace” theology of Chafer, Ryrie, and the Dallas Seminary, which one of their own (John MacArthur) declaimed; as well as the speculative excess and abuse of eschatology. While Christ proclaims “concerning that day and hour [of Christ’s return], no one knows, not even the angels of heaven, nor the Son, but the Father only” (Matthew 24:36, Mark 13:32); Pat Robertson (1982), Harold Camping (1994, 2011), and others consider themselves to have better relations with the Father than His very own Son. Consequently, Biblical prophecy is increasingly discredited, particularly Tim LaHaye’s “Left Behind” movie series.
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Recent triumphalist excesses by secularist and liberal forces have led to increasing socioeconomic persecution of Christians, not directly for their theological beliefs, but for the logical ethical extension of those beliefs. Religious liberty has become the cause célèbre of the day for those of many faiths. Having learnt nothing from the history of other nations, secularist and liberal forces are overplaying their hand, especially through the courts. There will likely be violent push-back, as religious and cultural conservatives feel their backs to the wall.
Diasporic American Jews are predominantly among the most secular (agnostic/atheistic) and liberal of constituencies in America, as epitomized by the Democrat cum Socialist, Bernie Sanders. And the long standing cosmopolitanism of these “Hellenistic” Jews, who have historically looked down even upon their “Orthodox” ethnic brethren, let alone those of other faiths, is in direct ideological and sociopolitical opposition to the beliefs and values of the Evangelical and the “American heritage” community.
As already noted, the cultural epicenter of Hollywood is controlled by Jews. There is an over-representation of Jews in the media and in Congress. But most importantly as a symbol of exagerrated political influence over the host nation, three of the current eight Supreme Court Justices are liberal Jews, constituting 37.5% of the court while Jews only constitute 2% of the general population. A decision, which is perceived to attack religious liberty, will have corollary effect of challenging even the loyalty of the most Philo-Semitic of Evangelicals, let alone the credibility of their Philo-Semitism among their peers.
The same corollary effect among “God and country” Evangelicals will occur if and when the Supreme Court becomes dominated by liberals, inclusive of these three Jews, and thereupon begin to undermine and dismantle, through sophistic interpretation of Constitution, long-held rights and privileges (i.e. right to bear arms). Just as the völkisch and nationalist sentiments among German conservatives in the Wiemar Republic gave rise to anti-Semitic sentiments and excess; judicial attacks upon the Constitution and other elements of the American heritage will cause likewise. The distinctive cultural heritage and irreligion of cosmopolitan Diasporic Jews will be seen as a direct and treasonous threat to the ideological and cultural heritage of the host nation.
Consequently, all these factors will result in a more precarious social existence for the American Jew as one of their primary bastions of political support diminishes in influence; and at best, loses its supportive zeal. At worst, Evangelicals may turn neutral or negative towards the State of Israel and their Jewish countrymen.
 Timothy P. Weber, On the Road to Armageddon: How Evangelicals Became Israel's Best Friend, Grand Rapids, MI: Baker Academic, 2004.  James Q. Wilson, “Why Don’t Jews Like the Christians Who Like Them?” The City Journal, Winter 2008, http://www.city-journal.org/html/why-don%E2%80%99t-jews-christians-who-them-13068.html.