Did Arab Christians take an active role in the crusades in the Holy Land or at any point on their trip to the Holy Land. Or were they victims of the crusaders? Did the crusaders typically differentiate between Christian Arab or Jew upon reaching Jerusalem?
Most of the information I have found indicates that the Arab Christians were caught in the crossfire between the Muslims and the Christian Crusaders. In fact, they were often slaughtered along with the Muslims. Most likely this was because the Crusaders did not want to risk being infiltrated by Muslims posing as Christians.
Ironically, the Crusades indirectly contributed to the decline of Christianity in the Middle East. At the time they took place, Arab Christians actually constituted a majority of the population in many areas. This was not only due to the deaths attributed directly to the Crusades, but also to the introduction of diseases brought into the area by the Crusaders. Also, the eventual and gradual diverting of internationl trade led to many of the Arab Christians leaving the area to follow the trade routes that they depended on for survival.
Ultimately, it does not appear that the Arab Christians at any time were ever significant contributors to the Christian war efforts during the Crusades.
The Crusaders never really cared about the religion. They only wanted to expand their sovereignty using the religion by inciting the people to go to war and free the holy land from the Muslims.
It was not because the Crusaders did not want to risk being infiltrated by Muslims posing as Christians but instead because of the nature of the Crusaders who came from Europe with little experience on what is called coexistence.
Europe as a continent did not accumulate such experience in it's historical inheritance if I may say that because it was a one religion society with some Jews persecuted from time to time. The same problem showed again with the native Americans few centuries later.
The Crusaders didn't merge together neither, each group of people stick together based on nationality. Christians were slaughtered with anybody and everybody else at the hands of their brothers in faith, a fact that led many of the Christian villages to forsake Christianity and join Islam.
Christian Commander led the army of Saladin, a Palestinian from Ako called Isa Alwam. Christians in the Middle East were ignored by the Christians of the west, maybe because they are loyal to their Arab nation. I am wondering what else is there?
Most of the Christian population were fairly non-militarised during the crusader period. SO generally they did not participate in military affairs. Exceptions being the Armenians and Maronites.
Various Armenian Christians were allied withe the crusaders, the county of Edessa was some sort of mixed state, with a lot of intermarriage with the locals and crusaders.
The Maronites (Christians in what today is Lebanon) did ally themselves with the crusaders.