What the article neglects to mention is that Christians who kill and conquer do it in SPITE of their source text, the Bible, in which Jesus says that He came to save men's lives, not to destroy them, that we are to treat one another as we would like to be treated, that those who hate are murderers in their hearts, and that Satan comes to steal, and to kill, and to destroy.
And mohammetans who kill and conquer do it BECAUSE of their source text, the Koran, in which their prophet Mohammet says to steal, and to kill and to destroy the infidels, to strike off their necks, to lie in wait for them, and to treat them as vermin and dogs.
But AP probably wants nothing to do with a good Comparative Religion course, which is probably what the Pope has in mind.
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That's the most important point.
The second most important point ignored by the writer is that the Crusades originated as an effort to drive back the Mohammedans who had conquered Christian lands.
And thirdly, the excesses of religious zeal in the middle ages, such as those related to the various Inquisitions, are highly exaggerated.