From Nicholas J. Healy’s review of John Connelly, From Enemy to Brother: The Revolution in Catholic Teaching on the Jews, 1933–1965 (Harvard University Press, 2012):

Connelly’s extensive research uncovered a surprising fact. “From the 1840s until 1965, virtually every activist and thinker who worked for Catholic-Jewish reconciliation was not originally Catholic. Most were born Jewish. Without converts, the Catholic Church would not have found a new language to speak to the Jews after the Holocaust.” … Confronted by a racist ideology that had made deep inroads in Catholic thinking in Germany and Austria, these converts discovered through bitter struggle that it was necessary to unconver and heal a deeply rooted contempt for the Jewish people.