Secularism has always been controversial. But today both the official secularism of constitutional republics and the secular ethic of liberal democracies are also being rocked by rapid social changes, resurgent religious identities and nationalisms, increasing migration, and many other factors. Secularism is an idea under siege by its opponents at the same time as conflicts within secularism pit its different aspects against each other in new tensions. ‘Hard questions and new conflicts’ considers secularism in practice, education as a feature of secularism, blasphemy and criticism of religions, religious expression in a secular state, religious diversity in the West, and resurgent political religion.