A year after an attack by ultraconservative Muslims raised the spectre of a wave of religious strife in Egypt, the Christian churches in Cairo’s Imbaba district have been repaired, with sturdy wooden rafters, fresh paint and portraits of the Virgin Mary and Jesus ready to be hung anew. But the deep wounds from those attacks and ensuing clashes, which left 12 dead, cannot be painted over. Coptic Christians, whose forefathers lived in Egypt before the arrival of Islam, had hoped that the 2011 uprising that ousted authoritarian President Hosni Mubarak would give them equal rights. Instead, things have worsened. Egypt’s...