Shall Jerusalem be divided again? Or should Israel remain sovereign over the holy sites of the three great faiths?

When the kingdom of Jordan ruled Jerusalem’s Old City between 1948 and 1967, Jews were barred from sacred sites, and the famous Hurva and Ramban synagogues were blasted into rubble. But since capturing eastern Jerusalem in the 1967 Six Day War, Israel has ensured Christians and Muslims free access to their holy places. Why? Because from its inception, the Jewish state was a liberal democracy, enshrining religious freedom in its declaration of independence and enforcing it through policy and law.

As Dore Gold shows in “The Fight for Jerusalem” (Regnery, 384 pages, $27.95) re-dividing Jerusalem probably would never have been on the international agenda if not for a series of diplomatic blunders by Israeli and American leaders, beginning with the 1993 Oslo Accords which raised the status of Jerusalem for the first time as an issue for negotiations, and culminating in the 2000 Camp David talks, in which Israeli Prime Minister Ehud Barak, backed by President Clinton, actively proposed handing over control of much of eastern Jerusalem to the Palestinian government of Yasser Arafat. (Arafat’s response was to turn them down and go to war.) Mr. Gold is in a position to know: As Israel’s former ambassador to the United Nations and head of the prestigious Jerusalem Center for Public Affairs, few writers today have the breadth of experience to turn this kind of insight into a powerful argument.

Mr. Gold begins his argument with a review of thousands of years of religious history concerning Jerusalem, with separate chapters dedicated to the place Jerusalem holds for Judaism, Christianity, and Islam. The thrust of the book, however, is a riveting — and terrifying — account of the forces arrayed against Western religious freedom today and what they would do to Jerusalem if it were it to fall into their hands.

The most obvious of these is fundamentalist Islam, which sees alien religious views, even certain Islamic ones, as heretical and a target for violence. The Taliban’s destruction of millennia-old Buddhist landmarks; Al Qaeda’s bombing of one of Shia Islam’s holiest shrines in Samarra, Iraq; and Hamas’s attack on the Church of the Nativity in Bethlehem give us a taste of what Palestinian Islamist groups like Hamas and Islamic Jihad would do to the Temple Mount, the Church of the Holy Sepulcher, and the City of David, were they to take control.

This possible outcome is why diplomats keep searching for “moderate” Palestinian leaders who seem Western enough to allow us to believe they would handle Jerusalem tolerantly. Mr. Gold shows us the peril of this illusion. Since taking control of territories in the West Bank and Gaza, the governments of Arafat and Mahmoud Abbas have overseen the destruction of ancient Jewish holy sites in Nablus (Joseph’s Tomb) and Jericho (the ancient synagogue); the harassment and steady eviction of the Christian population of Bethlehem; and the wanton excavation of the Temple Mount compound, destroying thousands of tons of one of the richest archaeological sites in the world.

There has also been destruction at the level of ideas. As Mr. Gold shows, Muslim and Arab leaders in the past recognized that Jerusalem was the location of Solomon’s Temple, but today it has become official policy, taught in schools and backed with pseudo research, that the most sacred place in the Jewish imagination — the Holy Temple in Jerusalem, built by King Solomon and maintained on and off for nearly 1,000 years — never existed. Echoing the Holocaust denial of their Iranian contemporaries, Palestinian leaders, writers, and scholars have embarked on a campaign of intellectual erasure, which Mr. Gold calls “Temple Denial,” aimed at undermining the Jewish claim to any part of the land.

Mr. Gold’s argument, therefore, comes down to this: Jerusalem cannot be divided without being effectively sacked — with its Jewish and Christian holy places cut off and even destroyed. The only solution for Jerusalem is to preserve its complete Israeli sovereignty, for this has been the only proven path to the respect for, and access to, holy sites of all faiths. “No other state or international body,” he writes, “can truly protect the peace, freedom, and religious pluralism of the Holy City for all mankind.” Compellingly argued and deeply researched, “The Fight for Jerusalem” reflects the wisdom of a seasoned diplomat. As a primer for the battles to come, it is dead-on.

Still, one wishes for more. The fear for Jerusalem’s loss cannot replace the classical love for Jerusalem, expressed in so many ways through the ages, which gave it sacred status in the first place. Mr. Gold tells us all about the sanctity of the city throughout history, but little about why it should be sacred in the future — for the religious Westerner, but also for the lover of democratic freedom.

For us to sacrifice on behalf of Jerusalem, we need to see it as a great city, with a character that is unique and worthy and alive. Jerusalem is not all history. It is the seat of government for perhaps the boldest experiment in conservative democracy: a nation that reveres both tradition and liberty and encourages the free and creative outpouring of our past into our future. It is a symbol not just of religion and preservation, not just of Judaism, Christianity, and Islam, but of the possibilities inherent in democratic government. In the past, Jerusalem has been contrasted with Athens and Rome; perhaps the proper opposition today is Brussels: not universalist and secularist like Europe, but delighting in its national and historical identity, its biblical mission, and its Jewish spiritual sensitivity. Unlike the European capitals, it is a city filled with children.

Mr. Gold’s book must be read and reread, for in the battle for Jerusalem lies the struggle for the soul of the West. If Jerusalem falls in the quest for “peace,” who will stop the creeping spread of relativism, institutionalized impotence, and ahistorical angst from making the West’s enemies even more emboldened? If we embrace Jerusalem and allow it to flourish, recognize it diplomatically and invest in it economically, that will say a great deal about how Western nations relate to their own past, their glory, and their future. Where Jerusalem goes, so go the rest of us.

Mr. Hazony is the editor-in-chief of Azure, a journal of public affairs published by the Shalem Center. He lives, and thrives, in Jerusalem.