Fifty people are dead, and millions around the globe are mourning, following the massacre at two mosques in Christchurch, New Zealand, on Friday. The terrorist attack unfolded during Friday prayer, when a lone gunman and avid white supremacist opened fire on worshipers while live-streaming the attack on Facebook. It was the deadliest shooting in the country’s modern history. The youngest of the dead is 3-year-old Mucad Ibrahim. Police have arrested and charged a 28-year-old Australian white supremacist named Brenton Tarrant with the killings. Tarrant published a manifesto praising President Donald Trump as “a symbol of renewed white identity and common purpose.” Trump has refused to acknowledge the global rise of white nationalism in the wake of the attack. We speak with Khaled Beydoun, a law professor at the University of Arkansas and the author of “American Islamophobia: Understanding the Roots and Rise of Fear.” He says, “There’s an underbelly of anti-Muslim animus that facilitates the emergence of the very brazen Islamophobia we see today, weaponized by people like President Trump or by terrorists on the ground in places like New Zealand who commit massacres like we saw on Friday.”