While the idiosyncrasy of post-Islamic Iran has been amply acknowledged by modern scholars, the Christian communities of what became the Arabic-speaking Middle East have remained largely invisible to us. It is as if the large Christian churches of Syria, Mesopotamia, and Egypt had fallen silent at the moment of the Muslim conquest. They are treated as having become religious “minorities” overnight. It is assumed that they were cut off as much from each other (by confessional rivalries) as they were cut off from their now-dominant Muslim neighbors. Yet nothing could be further from the truth.