This week, as Jews celebrate the Passover holiday, they are commemorating the Bible's Exodus story describing a series of plagues inflicted on ancient Egypt that freed the Israelites, allowing them to make their way to the Holy Land. But over the past century, another exodus, driven by a plague of persecution, has swept across the Middle East and is emptying the region of its Christian population. The persecution is especially virulent today.

The Middle East may be the birthplace of three monotheistic religions, but some Arab...