Papal Bull “Turbato Corde” issued by Clement IV to the Inquisitors of the Dominican and Franciscan Orders [Present-day Italy]: “With a troubled hear we relate what we have heard: very many reprobate Christians have abandoned the truth of the Christian faith and wickedly transferred themselves to the Jewish rite…Against Christians whom you find guilty of the above you shall proceed as against heretics. Jews who heretofore have induced Christians of either sex to their execrable rite, or whom you may find doing so in the future, you shall punish with fitting punishment.”
“Between Judaism and Christianity: The Semicircumcision of Christians according to Bernard Gui, his Sources and R. Eliezer of Metz,” Shaye J. D. Cohen, The Harvard Theological Review, 1 July 2001, Vol. 94(3), pp.285-321, See Shlomo Simonsohn, The Apostolic See and the Jews: Documents 492-1404, 236-7, no. 230. For the full Latin text. Accessed 5/23/2015