Pope John Paul II on Islam
“Whoever knows the Old and New Testaments, and then reads the Koran, clearly sees the process by which it completely reduces Divine Revelation. It is impossible not to note the movement away from what God said about Himself, first in the Old Testament through the Prophets, and then finally in the New Testament through His Son. In Islam, all the richness of God’s self-revelation, which constitutes the heritage of the Old and New Testaments, has definitely been set aside.
“Some of the most beautiful names in the human language are given to the god of the Koran, but he is ultimately a god outside of the world, a god who is only Majesty, never Emmanuel, God with us. Islam is not a religion of redemption. There is no room for the Cross and the Resurrection. Jesus is mentioned, but only as prophet who prepares for the last prophet, Muhammad. There is also mention of Mary, His Virgin Mother, but the the tragedy of redemption is completely absent. For this reason, not only the theology but also the anthropology of Islam is very distant from Christianity.”
(From JP II’s book Crossing the Threshold of Hope, 1994.)
St. John Damascene on Mohammed
“There is also the superstition of the Ishmaelites which to this day prevails and keeps people in error, being a forerunner of the Antichrist…. A false prophet named Mohammed has appeared in their midst. This man, after having chanced upon the Old and New Testaments and likewise, it seems, having conversed with an Arian monk, devised his own heresy. Then, having ingratiated himself into the good graces of the people by a seeming show of piety, he gave out that a certain book had been sent down to him from heaven. He had set down some ridiculous compositions in this book of his and he gave it to them as an object of veneration.”
—St. John Damascene, The Fount of Wisdom, “On Heresies”, 101.
(St. John, born in Damascus ca. A.D. 645 died in Jerusalem ca. A.D. 749. He was fluent in Arabic, Syriac and Greek, and had an intimate knowledge of Islam, having had a position in the government of the Caliph Abd-al-Malik before the latter’s hostility to Christianity drove him away. He thereafter became a monk.)
St. Thomas Aquinas on Mohammad
“The point is clear in the case of Mohammad. He seduced the people by promises of carnal pleasure…and he gave free reign to carnal pleasure. As proofs of the truth of his doctrine, he brought forward only such as could be grasped by the natural ability of anyone with a very modest wisdom. … those who believed in him were brutal mean and desert wanderers, utterly ignorant…through whose numbers Mohammad forced others to become his followers by the violence of his arms. “
(St. Thomas Aquinas, Summa contra Gentiles, Bk 1, [4])