The Prophet Muhammad knew Christians in his lifetime and respected them along with Jews as "People of the Book." Because of their monotheism and roots in the revealed Jewish Bible, the Prophet and his successors extended conquered Christians (and Jews) more freedoms than conquered pagans.
In the approximately 1,300 years of history since the life of the Prophet, the relationship between Christianity and Islam has rarely been harmonious. As it spread, the Muslim Empire quickly conquered much of the Judeo-Christian Holy Land and the Christian Byzantine Empire. The Christian Crusades of the 11th through 13th centuries, waged in large part against Muslims, served only to widen the divide between the two faiths. Constantinople, the "New Rome" and the center of Eastern Orthodox Christianity, fell to the Turks in 1453 and has lived under Islamic rule ever since.
In recent centuries, mutual distrust between Christians and Muslims has continued to grow. On the other hand, some have pointed out that the conflict has more to do with political tensions and divergent cultural worldviews than with religion, and efforts have been made by both Christians and Muslims to find common ground and engage in respectful dialogue.
To illustrate the similarities and differences between the two largest religions of the world, the following chart compares the origins, beliefs and practices of Christianity and Islam. Please note that numbers are estimates and beliefs and practices are oversimplified for brevity's sake.