Despite predictions to the contrary, religion is not disappearing. By now many proponents of the secularization thesis—the argument that with modernity the world is becoming less and less religious on a path to a religion-free world—have admitted their error and acknowledged that religion is well and thriving in contemporary life. The rapidly increasing and deepening religious pluralism in many places around the world raises the problem of how people of radically different faiths can live together.

The essays gathered here suggest that secularism might be part of the answer. Secularism, they argue, is not anti-religious or simply the absence of religion; rather it involves the attempt to create a public realm shaped by respect for others and concern for their rights—a place in which deep differences can coexist. For a secular state is (ideally) one that enforces no one religion; treats people of all religions with equal respect; and preserves a public space for the free exercise and expression of religions. Secularism, in these pages, is thus construed as the friend of all religions, and the foe or champion of none.

What emerges from these pages is actually not one secularism, but rather a range of secularisms—French, American, Indian, and others—that can be compared, evaluated, and improved upon. Just as religious pluralization means that we need to think more deeply about particular religions, rather than in the generic category of “religion,” so we need to think about secularisms—actual ways in which states manage the religious diversity in their midst. How can we live together with our deepest differences? How can we live in common purpose with those of different faiths and no faith, building a common world together? These are crucial questions for humanity in the twenty-first century, ones that we avoid at our peril. Unless we arrive at better models of religious pluralism, we will face more and more conflict and violence. The essays gathered here ask us to consider the proposal that religious pluralism requires secularism.