Another good one, Paul.
1) Per National Geographic, 60% of the Middle East was Christian at the time of the first Crusades. This makes sense as when one visits Jerusalem, one sees the degrees of Coptics, Armenians, Ethiopians, Maronites, Assyrians, etc etc and their large presence. Apparently, Muslims of the times considered them "of the faith" (remember Judaism, Christianity, Islam all share the Old Testament) and "children of Abraham". The Muslims simply used the Dhimmi System to make them pay an extra tax (a good deal since they were then not bound by strict Islamic monetary laws). At this time, Islam and Christianity might have been as different as Catholicism and Mormonism.
2) The need for Christian pilgrimages to Jerusalem were legitimate. The Templars sprang up as pilgrimage guides. They soon compared notes with Jerusalem residents and learned that the Roman version of Christianity had been "laundered" to suit Rome (as opposed to Gnostic and Jewish versions). They thus became the guardians of a kind of universal faith. For better or worse, Jerusalem remains open to pilgrimages of the three major faiths to this day. Personally, during the tiny amount of time we were allowed to visit the Temple Mount, I did not appreciate being heckled by Muslims, but oh well.
3) Again per National G., the two armies almost did not reach each other, as en route the forces of Rome and Constantinople fought one another, as did the forces of Shiites and Sunnis (funny). In the first Crusade, the Christians indiscriminately killed all faiths in Jerusalem (including Jews and Christians) not knowing the difference. Famously, when Saladin retook Jerusalem, he spared lives. He became known for his grace in victory.
4) Much of the Crusades were a kind of comedy of errors on both sides, when the three major faiths had a historic chance of creating freedom of worship and religious peace. Today, things may have gone too far downstream. In particular, I have noted that Jews have historically suffered more at the hands of Christians than Muslims (most Muslim-Jewish trouble began with the creation of Israel?)
