God, I hate sentences like this one:
>>>By modern standards, the Christians and Jews (the dhimmi) were often treated as second-class citizens, but it was at least a kind of pluralist equilibrium that had no parallel in Europe until the 1950s.<<<
There were also slave owners in the antebellum South who treated their slaves well, too. They were still slaves. Dutch families hid Jews in their attics. There were Hutus and Tutsis who didn’t take part in the carnage. And on and on I could go.
If you’re a second class citizen, you’re not really a citizen of any culture worthy of your participation. Jeez.
I understand where you're coming from. But during Christianity's many persecutions of religious minorities, the only choices given to them were to stay but convert, stay without converting and be killed, or don't convert and leave. (In many cases, their possessions were confiscated, whether they converted or not, and Christian greed* for these possessions may in fact have been an important reason for their persecution). But even if they left, they needed some place to go. The Muslim empires was where many ended up going, because few Christian countries offered large numbers of non-Christians refuge on even marginally acceptable terms.
Note that I'm not a great fan of Islam, but the fact is that in the distant past, non-Christians received more tolerance from Muslim empires, and persecuted religious minorities in Christian lands voted accordingly, with their feet by leaving Christendom for the lands of Islam. In the modern era, the pendulum has clearly swung the other way, of course.
* When historians say that religious minorities were relatively well-treated in the Muslim empires, that's exactly what they meant - they got better, but not ideal treatment from their Muslim overlords. A lot of Jews ended up as high officials in Muslim empires. How many Jews achieved this status in the West before the 19th century? As Jews, rather than as Jews converted to Christianity?