This whole thread begs the question of how Islam started out in the 7th and 8th centuries by invading Christian lands and massacring all Christian inhabitants who would not immediately convert to Islam. There have been wars started by Muslims in every century since. Any good history book can inform one on this.
"While few contemporary Christians would defend the idea of the crusades or its most gross offenses, we must not overlook a simple reality. The Christians sought to counter Islam's remarkable military conquest and preserve their geographic strongholds from being overrun. By the eighth century, one half of all Christians lived under Islamic rule" (Church History in Plain Language, 4th edition, by Bruce Shelley, revised by R. L. Hatchett in 2013, p. 196).
"The good works (of Islam) consist of prayers, fastings, the giving of alms, and at least one pilgrimage to Mecca. But the best of all is war--even to death--against the unbelievers. A drop of blood shed in sacred war is of more avail than two months of fasting and prayer" (A History of the Christian Church, by Lars P. Qualben, 1942, p. 146).
