Pengetahuan Kristen terawal yang didomentasikan mengenai Muhammad timbul dari sumber-sumber Bizantium, yang ditulis tak lama setelah kematian Muhammad pada 632 M. Dengan Perang Salib pada Abad Pertengahan Tinggi, dan peperangan melawan Kekaisaran Utsmaniyah pada Abad Pertengahan Akhir, pandangan Kristen terhadap Muhammad makin menjadi polemik, yang beralih dari klasifikasi sebagai bidah ke penggambaran Muhammad sebagai pelayan Setan atau Antikristus, yang mengalami penyiksaan abadi di Neraka.[5] Pada Abad Pertengahan Akhir, Islam secara lebih mencolok dikelompokan dengan Paganisme, dan Muhammad dipandang sebagai penyembah berhala yang terinspirasi oleh Iblis.[5] Sebuah pandangan yang lebih longgar atau halus terhadap islam baru berkembang pada zaman modern, setelah kekaisaran-kekaisaran Islam menghentikan ancaman militer akut ke Eropa (lihat Orientalisme).
Criticism by Christians [...] was voiced soon after the advent of Islam starting with St. John of Damascus in the late seventh century, who wrote of "the false prophet", Muhammad. Rivalry, and often enmity, continued between the European Christian world and the Islamic world [...]. For Christian theologians, the "Other" was the infidel, the Muslim. [...] Theological disputes in Baghdad and Damascus, in the eighth to the tenth century, and in Andalusia up to the fourteenth century led Christian Orthodox and Byzantine theologians and rulers to continue seeing Islam as a threat. In the twelfth century, Peter the Venerable [...] who had the Koran translated into Latin, regarded Islam as a Christian heresy and Muhammad as a sexually self-indulgent and a murderer. [...] However, he called for the conversion, not the extermination, of Muslims. A century later, St. Thomas Aquinas in Summa contra Gentiles accused Muhammad of seducing people by promises of carnal pleasure, uttering truths mingled with many fables and announcing utterly false decisions that had no divine inspiration. Those who followed Muhammad were regarded by Aquinas as brutal, ignorant "beast-like men" and desert wanderers. Through them Muhammad, who asserted he was "sent in the power of arms", forced others to become followers by violence and armed power.
^Yohanes dari Damaskus, De Haeresibus. See Migne, Patrologia Graeca, Vol. 94, 1864, cols 763–73. An English translation by the Reverend John W. Voorhis appeared in The Moslem World, October 1954, pp. 392–98.