As Muslims prepare to erect a mega-mosque near the site of the 9/11 atrocities, it is well to reflect that the sort of tolerance, or indifference, that allows them to do so, is far from reciprocated to churches in the Muslim world. I speak not of Islamist attacks against churches—such as the New Year attack in Egypt that killed 21 Christians; or when jihadists stormed a church in Iraq, butchering over 50 Christians; or Christmas Eve attacks on churches in Nigeria and the Philippines. Nor am I referring to state-sanctioned hostility by avowedly Islamist regimes, such as Iran's recent "round...