Chabad, also known as Lubavitch, is a global organization based in Brooklyn that is dedicated to strengthening and enriching Jewish life by providing religious, educational, social and cultural services around the world. Representing a branch of Hasidic Judaism, the organization maintains a vast network of emissaries and Chabad houses that offer hospitality and engage in outreach. They serve local Jewish communities and often draw in crowds of secular Jews traveling in far-flung places during holidays. The group’s chapter in Bondi Beach in Sydney, Australia, was hosting a Hanukkah event on Sunday when gunmen targeted the celebration, killing at least 11...