Far below the piercing spires atop every Church of Jesus Christ of Latter-day Saints chapel rests a sign that beckons, “Visitors welcome” – a testament to the faith’s robust evangelizing efforts. But on Sunday morning, a former Marine and Iraq War veteran took advantage of the denomination’s open arms – plowing his truck into an LDS church in Michigan, shooting worshippers with an assault weapon and setting the chapel on fire. At least four people were killed at the church in tranquil...