The library of books on the Israeli-Palestinian conflict is vast, and it grows every year. John Judis's "Genesis" claims to distinguish itself by focusing on President Harry Truman's efforts "to resolve the conflict between Jew and Arab." Mr. Judis thinks that we can learn from Truman's failures and wants readers "to approach the subject from when the conflict actually began." But "Genesis" distinguishes itself in another way: It isn't so much a history as an inquisition—one that weighs the moral balance of the conflict from on high and finds Zionism, and its American supporters, guilty.

The author, a senior editor of the New Republic, begins by surveying the 50 years of Jewish-Arab tensions in Palestine that preceded the birth of the Jewish state in 1948. While rehashing the origins of both Zionism and Palestinian nationalism, he casts the movement for Jewish statehood as an inherently colonialist enterprise and the Arabs as its victims. The Zionist pioneers settling in Palestine, the author writes, committed "many of the sins that Western European countries had visited upon native populations," displacing locals and stifling their "natural development." In making this charge, he equates Europe's mightiest powers with its greatest victims, the Jews—a stateless people seeking refuge in their ancient home by legitimately purchasing and cultivating land.

Throughout this preamble, Mr. Judis accuses the Zionist movement of rejecting compromise and "social justice." But regarding the most heinous Arab actions—such as the 1929 massacre of the Jewish community of Hebron or the five-country invasion of the nascent state of Israel in 1948, which followed the Arabs' rejection of the first United Nations peace plan—the author is more forgiving. These he largely plays down or characterizes as understandable responses to Jewish provocation.

There is a good reason why this partisan early narrative sounds familiar: It is nearly 200 pages of mostly regurgitated secondary sources. If Mr. Judis were dedicated to telling an original story about Truman, he shouldn't have devoted half of his book to this carbon-copy history. But he isn't primarily concerned with how Truman came to recognize the state of Israel or even, really, with the fate of Palestine. Instead, Mr. Judis is consumed by what he views as the pernicious influence of diaspora Jewish Zionists on the British and American governments.

The author traces the sinister sway of Zionism to the drafting of the Balfour Declaration, the 1917 document in which Britain pledged to establish a Jewish national home in Palestine. Chaim Weizmann, a chemist whose scientific discoveries greatly aided the British during World War I, "charmed his way up the ladder of authority until he reached the top," Mr. Judis writes, and then suckered some key British figures into supporting the Zionist cause. When, after the war, others attempted to dilute Britain's commitment to the Balfour Declaration, Zionist activists in Britain consistently "blocked" their efforts.

A running theme is that had these Jews been patriotic Britons, they wouldn't have lobbied for Zionism. Mr. Judis uncritically cites Prime Minister H.H. Asquith receiving a pro-Zionist memo from Herbert Samuel, a Jewish cabinet member, and noting in a private letter that "it is a curious illustration . . . that 'race is everything' to find this almost lyrical outburst proceeding from the well-ordered and methodical brain of [Samuel]." Mr. Judis thus deploys the bigotry of yesteryear to bolster his contemporary arguments.

What British Zionists did in London, Mr. Judis claims, American Zionists would do in Washington. By the end of the 1930s, Zionist activists, apparently not as all-powerful as "Genesis" would have readers think, failed to prevent Britain from decisively abandoning the Balfour Declaration. But as British power in the region receded following World War II, both Zionists and Arabs realized that their fortunes rested with the United States. Truman, who had no Middle East experience, was advised by Britain and by the U.S. Defense and State Departments to side with the Arabs. For three years, he anguished over whether to support Zionism. He weighed Arab sentiment against Jewish plight and political expediency against his sense of morality, while always seeking to uphold U.S. national interests.

"Genesis" reduces this tortuous deliberation into a simplistic tale of Jewish bullying. In its few pages of background on Truman's relationship with Jews and Zionism, the book discards well-documented complexity to insist that the president didn't sympathize with Jewish sovereignty. Truman, Mr. Judis says, was browbeaten by "unrelenting and obnoxious" pressure from Zionist activists. The president would ultimately bow before Zionist advocates "not because he believed in their cause," but out of electoral concerns. Mr. Judis accuses one figure, Abba Hillel Silver, of putting "the Zionist cause above party politics—and, in effect, above any domestic agenda." If a Democrat failed to fully endorse Zionism, Mr. Judis writes, Silver "tried to use the Jewish vote and Jewish contributions against him." Here and elsewhere, "Genesis" treats issue-driven voter lobbying, a staple of American democracy, as if it were high treason.

The author blames Truman's endorsement of a Jewish state—as opposed to a binational state in Palestine—on American Jewish liberals, who are the true targets of "Genesis." Mr. Judis is mystified by the fact that liberals who "supported labor rights, civil rights, and the first amendment," such as Supreme Court Justice Louis Brandeis, could also support Zionism. In doing so, he says, these otherwise stalwart progressive champions "abandoned their principles."

Zionism, for Mr. Judis, is a kind of sin against liberalism. Near the end, he quotes a saying of Jesus: "For what shall it profit a man, if he shall gain the whole world, and lose his own soul?" and castigates Israel's Jews for having "gained a world of their own, but at the expense of another people." An author who brandishes his liberal commitments at every turn ends up invoking a Christian teaching on greed to condemn the Jews for sacrificing another people at the altar of their own interest.