It is always noteworthy when a 21st-century Pope quotes a 14th-century Byzantine. Pope Benedict XVI did just that at a speech given at Regensburg University.
Benedict addressed the issue of Islamic holy war, noting that it was "against God's nature." He quoted, interestingly, a 14th-century Byzantine Emperor, Manuel II Paleologos.
Show me just what Muhammad brought that was new, and there you will find things only evil and inhuman , such as his command to spread by the sword the faith he preached.
Benedict went on to explain the emperor's repudiation of, and unreasonableness of, the use of violence in spreading faith.
One spectator was impressed, noting that "Muslims aren't going to take us seriously until we become conscious of our own values."
Exactly so. Read here.