It is frequently asserted that Islam is insane and irrational, and that the actions of devout Muslims are therefore capricious and without logic. This is hardly the case. Muslims are generally quite rational — they just have very different logical premises than we do.
Muslims do not commit bizarre, inhuman acts for no reason. They do so for quite precise reasons, which may be determined from reading their source texts (plus tafsirs, or authenticated exegeses) closely. If you begin with bizarre, inhuman premises, and follow the rules carefully based on them, then PRESTO! — you’re a Muslim. A good Muslim. You’re a devout servant of Allah, a god who demands that you follow his intricate instructions down to the minutest detail.
Every time someone refers to a jihad massacre as a “senseless tragedy”, he reveals that he has not done due diligence with respect to Islamic law. Those acts are not senseless, not in the slightest. And they are not “tragedies”, they are atrocities. Intentional, deliberate, methodical atrocities carried in rigorous compliance with Islamic law.