All religions say the same thing! When christianity had the power, they burnt 50 million witches in Europe (including Copernicus and nearly Gallileo) Today is the day of islams folly and stupidity! And let no-one say that the slayings aren't religious but a few fanatical head bangers, they were brought up to "believe" in iron-age obscurantism!!
While the Quran allegedly was handed down by an angel, the writings have been translated into the bedrock of religion somewhat like the bible is for Christians. Literal interpretation exhorts Muslims to combat infidels. Scholars parse words and suggest that jihad does not mean to kill infidels, it means to combat those who fight against it. Unfortunately, the scholars interpretation remains in the classroom and the populist sentiment is that the Quran is literally interpreted as destroying the infidels and their spawn. This rhetoric endangers anyone who is not a true believer.
The Koran does advocate the killing of infidels. The Koran also calls on the death of people who decide to leave the faith. The Koran is a very brutal book cover to cover. But this isn't just the Koran that is like this, but many other holy scriptures--the bible included.
Actually, yes, I do believe the Koran advocates killing of infidels. I don't happen to have a copy so I can't look it up, but I have seen passages cited and quoted that order the faithful to kill the infidel. And I've had Islamic friends who, before the recent hostilities, talked about killing people who were "infidels." Supposedly it is a religion based on love like Christianity, but like Christianity there is also a lot of violence.
The Koran advocate the killing of infidels. They got the idea somewhere in there. But, to be fair, the Bible is full of examples of God's wrath on people who weren't "his people". The Old Testament especially is full of stories where God directs "his people" to go and smite this or that heathen people.