Normandy, Istanbul, Dhaka, Nice, Baghdad, Orlando: Why?

Peter Bergen wrote for CNN explaining the recent ISIS attacks: 

Mass casualty terrorist attacks in Orlando, at the Istanbul airport, at a café in Bangladesh, a market in Baghdad, the Bastille Day celebration in Nice, and on Tuesday the murder of an elderly priest in Normandy, all carried out by ISIS or in the name of ISIS. And that's just in the past several weeks.

After each one of these attacks the first question is: Why? Why would anyone kill complete strangers who are dancing at a nightclub, or eating at a restaurant, or folks attending a holiday fireworks display, or an 86-year-old priest?

There are five deep historical currents that are influencing these events. At the macro level, ISIS is not itself the problem — though it certainly amplifies existing problems — but rather it's the symptom of five major problems that are driving jihadist terrorism around the globe and will continue to do so even when ISIS is contained and largely defeated.