Why was Jerusalem important to the muslims?
According to muslims , Jerusalem was the place near witch they turned in prayer until prophet muhammad changed it to mecca. Jerusalem is also the place that started in the Quran that prophet muhammad was taken up to heaven. That happened at the furthest mosque also that is of great significance to jews, christians and muslims.
The reason for the crusades based on your groups point of view?
According to muslims political theorists, the sultan was the most important seruant. It seems very unlikely that from Barkiyarqu's perspective present themselves before him, but with no better result.
The effects of the crusades on muslims?
It was overall a negative effect.The muslims where already behind intellectually and theologically and then the crusades got them to where they where they should have been .The Muslims did not see it as a holy war until Nur al-Din escalated it in the Second Crusade and the Third Crusade with Salah al-Din.
Muslims perceptions of the other groups?