Future Tense is a fine pun for the title of a book about, in the words of its subtitle, Jews, Judaism, and Israel in the Twenty-First Century. For the last two centuries or so, thinking about the future has made Jews very tense—rightfully so, you might conclude, looking at the historical record. If you gave a pessimistic answer to what was long known as “the Jewish question” in 1840 (the year of the Damascus Affair), or 1881 (when pogroms swept Poland), or 1933 (when the Nazis took power in Germany), you would have found your despair amply justified. But in this new book, Jonathan Sacks, a rabbinical scholar and religious thinker, and also the Chief Rabbi of Great Britain, argues that what was true of the past is not true of the present.

In 2010, Sacks writes, what Jews need is not anxiety but confidence, not withdrawal from the world but a new embrace of it: “It is my considered view that, in this tense and troubled century, Jews must take a stand, not motivated by fear, not driven by paranoia or a sense of victimhood, but a positive stand on the basis of the values by which our ancestors lived and for which they were prepared to die. … Now is not the time to retreat into a ghetto of the mind.” Sacks’s forceful book lays out his vision of what that “positive stand” might look like, in terms of Jews’ relations with one another—in Israel and around the world—and the wider world, including both secular science and culture and members of other religious faiths.

Sacks is ideally positioned to argue for this sort of Jewishness—pious yet uncloistered, self-assured but not separatist, engaged with the world but not emptily “universalist”—because it is just the sort of Jewishness that he himself lives. As Chief Rabbi, a position with no equivalent in the United States, he is an official spokesman for British Jewry, who often finds himself sitting on government commissions, leading interfaith dialogues, offering opinions on the BBC, and dealing with various delicate social and cultural flashpoints. (There is, in fact, a certain amount of vanity on display in Future Tense: Sacks wants us to know about his close personal friendships with figures like Isaiah Berlin and Teddy Kollek.) These experiences have convinced him that Jews are by no means as friendless as they may sometimes believe.

To American Jews reading the news from Britain, it can often seem that Britons’ interest in Judaism mainly takes the form of demonizing Israel and casting suspicion on its Jewish supporters. But Sacks insists otherwise. “Jews cannot fight anti-Semitism alone,” he writes, and he reports that he has found Britons of all faiths—Anglican, Catholic, Hindu, even some Muslims—ready to join the fight against “prejudice and hate.” In fact, he persuasively argues, Jews are in some way destined to lead the fight for liberalism and tolerance in Western societies, because for two thousand years they have been “the quintessential Other” in Christian and Muslim civilization. “That is Judaism’s great contribution to humanity: to show that one can be other, and still human.”

What is crucial to this historical coalition-building, and to Sacks’s whole vision of Jewish assertiveness, is that he speaks not just as a community leader but also as a religious leader. Here Sacks’s particular kind of Modern Orthodoxy turns out to be ideal for his task. Few lay figures in the American Jewish leadership would affirm, as Sacks unhesitatingly does, that God literally did choose the Jewish people to play a unique role in the world, and that the Bible can be read as the actual expression of God’s will. (There are Reform or Conservative rabbis who would also demur from these positions.) On the other hand, increasingly few Orthodox rabbis have the willingness or the authority to engage with the secular world on Jewish terms. “A rabbinate untrained in the wisdom of the world,” Sacks writes, “will find itself irrelevant to those immersed in the world. A Judaism divorced from society will be a Judaism unable to influence society.”