Muslims were expelled ten years later.
Wanderings is a great book, but it is one author's interpretation of history, and, did you miss where Potok discussed the rest of Middle Ages and Reformation Europe's attitudes and actions towards the Jews?
Did you miss the First Crusade's knights using German Jews as a warm-up exercise and practice training before going off to defeat the Muslims in Jerusalem, killing tens of thousands of Jews?

"Convert  or die!" has never been exclusive to Islam.