“The best news is when you call get ready for jihad,” Mustafa Mousab Alowemer wrote in a public housing project in Pittsburgh. “I will spill my blood for the victory of my religion.” Northview Heights, the low-income housing project, is 90% African-American. Or at least it was. Then a flood of Syrian Muslim refugees showed up. Obama had promised to admit 10,000 Syrian migrants in 2016. The terrorist who plotted a massacre at a black church was one of them. The Alowemer clan arrived at JFK airport in New York City. The same airport through which other terror refugees, including...