Though the status [of Jews] was not recognized de jure in the canon law of the Christian Church, it was no more possible for Christianity than it was for Islam to cut the ground of its own moral claims to theological validity from under its own feet by proscribing another higher religion which was not only older than it was, but was its forerunner according to its own contention. [Footnote: The historical relation of Christianity to Judaism explains why the Christian Church never extended its tacit toleration of Judaism to an Islam which was in one aspect a post-Christian reversion to Judaism from Christianity. In the Christian view the tolerance morally due to a truly though imperfectly inspired pre-Christian approximation towards Christianity could not properly be extended to a perverse backsliding from the Christian summit of religious attainment.]
Christians did not treat Jews better than Muslims. They had higher regard for Jewish theology, but where Jews had no civil rights, religious toleration had no meaning.
Islam’s traditional respect for the older religions is disappearing in some quarters.
A Study of History, Vol VIII, OUP, 1954