The High Priest, the Pope and I – Ten Questions for Rabbi Cardozo by Rav Ari Zeโev Schwartz
In Jewish Thought and Philosophy, Maimonides and Rav Kook by Rabbi Nathan Lopes Cardozo
However blasphemous this may sound, the Kohein Gadol was to be the original pope. Basically, the papacy is a Jewish function, tasked not with the mission of spreading the gospel, but rather promulgating monotheism, morality and the Torah, as far as it is applicable to the non-Jewish world.