Quran is complete guidance for mankind

during a mass shooting that often occurs at schools in America. Who's wrong?
the weapons creator, the creator of the guide "how to use a gun", the perpetrator, or even the God who created the perpetrator?

Quran is complete guidance for mankind ..which there's : the law of war, eating, looking for sustenance, sex, science (which is evident during the Qur'an was revealed it could not be explained (such as atoms, a process formation / creation of the human body, the circulation of celestial objects,  and so forth)), and so forth :)

so.. sorry if there are bad examples of Muslims, who read the "law of war" to "a banquet or social event"
..because that's human (not because of their religion) but how they maintain the passions
..remember Nazi, Serbia, Ireland and many other examples