REGENSBURG, Germany— Pope Benedict XVI said yesterday that Islamic holy war was against God's nature and invited Muslims to join in a peaceful cultural dialogue.

In a speech at Regensburg University, Benedict made an unusual reference to jihad, or holy war — a concept used by Islamic extremists to justify suicide bombings and other attacks.

Benedict's address was about faith and reason, and how they cannot be separated and are essential for "that genuine dialogue of cultures and religions so urgently needed today.''

Citing historic Christian commentary on holy war and forced conversion, the Pope quoted from a 14th-century Byzantine emperor, Manuel II Paleologos.

"The emperor comes to speak about the issue of jihad, holy war," the Pope said. "He said, I quote, 'Show me just what (Islamic Prophet) 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.'"

Clearly aware of the topic's sensitivity, he added, "I quote," twice before pronouncing the phrases on Islam, while neither explicitly agreeing with nor repudiating them. "The emperor goes on to explain in detail the reasons why spreading the faith through violence is something unreasonable,'' he said.

"Violence is incompatible with the nature of God and the nature of the soul," the Pope said.