Gavriel and Rivka Holtzberg were living in Mumbai with an incandescent purity of purpose. This was a couple who knew personal tragedy: Apart from their almost-miraculously saved son Moshe, who turned two on Saturday, a second child had died of a degenerative disease earlier this year and a third is unwell. This was a couple who had embraced personal challenge: Five years ago, as part of the late Rabbi Menachem Mendel Schneerson's global army of Jewish outreach troops, they chose to relinquish Western creature comforts and head into the distant Indian unknown. The certainty that their work was right and enlightened is audible in every syllable that Gavriel enunciates in a short video clip, widely circulated these last few terrible days, where he traces the brief history of Chabad in Mumbai: He and "Rivky" got going "in December 2003 - just in time for Hanukka," he recalls with brisk satisfaction. They started off their operation in a small room in a three-star hotel downtown, "giving shiurim [Torah classes] in that small space and having Shabbat meals without a kitchen." As it grew and moved into its own premises, he continues, the Chabad center became a place where hundreds came to eat kosher, thousands of Torah classes were given to young and old, and local Jews and travelers alike could enjoy Shabbat and the festivals. All over the world, thousands of emissaries like the Holtzbergs are doing similar work, generally staying for life in the locales to which they are first dispatched. The goal, as Rabbi Dovid Eliezrie from California told me at the annual gathering of these shlichim in New York four years ago, is to advance Schneerson's ideals, namely "to accept every Jew nonjudgmentally and to encourage him to grow in his observance and his knowledge of Torah." The ultimate aim: "To transform the world into a place of goodness and holiness and thus to bring the Messiah." At the Holtzbergs' Chabad outpost, that noble purpose of transforming the world for the better was overwhelmed by men who have forsaken all connection to such ideals. Chabad insists that it is not deterred. "Forge ahead with courage and fortitude in the service of our people and mankind, to make this world a better place to live for all," its emissaries were told by Rabbi Yehuda Krinsky on Friday, after the death of the Holtzbergs and others in the Mumbai Chabad House had been confirmed. Man's capacity to do the unthinkable to his fellow man continues to astonish and horrify afresh. Reconciling such brutality with the notion of an abiding divine presence remains unfathomable. But what must be fathomed and internalized - amid the mourning for Gavriel and Rivka Holtzberg, their murdered guests in a house of elevated purpose, and the hundreds more people slaughtered in the terrorist onslaught of the past few days - is the gravity of the threat to our most basic values, and the imperative to confront that threat effectively. The premeditated assault on Chabad House and Mumbai's other soft targets is only the latest bloody declaration of war by the death-cult Islamists, seeking now to destabilize India, but ultimately threatening all of our freedoms. To its abiding moral and practical detriment, much of the international community nonetheless shies from this reality, clinging to the self-evidently risible notion that there are specific, legitimate grievances motivating the murder, and that these grievances can be sated and normal service resumed. In truth, of course, it's us or them. And the appalling "success" of this most recent, sophisticated assault on another free society, this latest benighted exercise in a campaign of global destabilization, exposes the incompetence of our defense. The free world must first acknowledge the scale of the challenge, and then set in place the cooperative security, intelligence and legal frameworks to meet it. For only then will all the other Gavriel and Rivka Holtzbergs, and all those among us who revel in the fragile, precious miracle of life, be free to enjoy it.