But the most interesting conquest of the Seljukian Turks was that of Jerusalem, which soon became the theatre of nations. In their capitulation with Omar, the inhabitants had stipulated the assurance of their religion and property; … and the sepulchre of Christ, with the church of the Resurrection, was still left in the hands of his votaries. Of these votaries, the most numerous and respectable portion were strangers to Jerusalem: the pilgrimages to the Holy Land had been stimulated, rather than suppressed, by the conquest of the Arabs; … The harmony of prayer in so many various tongues, the worship of so many nations in the common temple of their religion, might have afforded a spectacle of edification and peace; but the zeal of the Christian sects was imbittered by hatred and revenge; and in the kingdom of a suffering Messiah, who had pardoned his enemies, they aspired to command and persecute their spiritual brethren.
Edward Gibbon (1788), The History of the Decline and Fall of the Roman Empire, Vol. 5, Chap. 57, on Jerusalem under the Muslims and the motivation of the Crusades