Islam was founded in 610 AD. Mohammed died in 632 AD. During the rest of that century, Islam expanded throughout the Sinai Peninsula. The next century saw the area that is today known as Israel falls to Islam. This expansion continued at a rate that was and is unprecedented in history. As was common in those days, this expansion was mainly by force of arms. The crusades began in the late 12th century. The crusades were actually a reaction to the constant warfare on the Eastern Roman empires southern flank. The dozen or so crusades covered a period of about 150 years and were ineffective in ending the defensive posture of Christianity in Europe.
Once the crusades ended, Islam resumed its assault on southern Europe. The fall of Constantinople in 1453 formally ended what was left of the old the Roman Empire. The sieges of Vienna in 1529 and battle of Vienna in 1683 are seen as the high-water mark for Islam in central Europe.
In 1804, the U.S. fought a small-scale war against the Barbary pirates. The pirates had seized some U.S. ships and were demanding Tribute. Tribute is the ‘poll tax’ that is paid by infidels living in Muslim land to Muslim authorities. By extending this concept to Muslim waters, the pirates were extending this concept. As you know, the U.S. sent our battle fleet over there, assaulted the harbors where our ships were anchored, killed all that attempted to stop us, and burned our ships.
The point that I am attempting to make here is that the sword has spread Islam, and this has not ended. Right from its inception, jihad as armed struggle was and is an important component. "Kill the occupiers" of Muslim land was and still is an important and ‘authentic’ law.
Although countless wars have been started in the name of various ‘religions’, Islam is fundamentally different from Christianity in a number of ways. One way is that the wars that Christians have begun were excuses and interpretations from the Bible. The Bible does not spell out the rules in which you can kill and/or enslave others. In fact, the Bible does just the opposite. However, the Koran does spell out organized violence. You can ‘kill occupiers’, infidels, apostates, rebels, bandits and married women who have committed adultery to name some. These are ‘authentic’ laws that have been and still are far more strictly enforced than the 10 commandments. This has been a basic issue in the constant warfare between these two religions since Islam's inception.