Thousands of mourners gathered under tight police security at Sydney’s Bondi Beach on Sunday evening to mark a week since two gunmen targeting a Hanukkah festival killed 15 people. Since then, Australian governments have been galvanized into action on countering antisemitism and tightening already strict national gun controls. Prime Minister Anthony Albanese, his predecessors John Howard and Scott Morrison, and Governor-General Sam Mostyn — who represents Australia’s head of state, King Charles III — were among the dignitaries at the commemoration that drew more than 10,000 people. “This has to be the nadir of antisemitism in our country,” New South...