Simply put "What Caused ISIS?"

I decided that a simple answer would be best.

What caused ISIS is the 200,000 Sunni Deaths and tortures by the Assad regime in Syria combined with the Maliki Iraqi government taking away all the rights of Sunnis in Iraq and killing many leaders or driving them into exile.

This is the simplest explanation of what caused ISIS.

Then you can add the 9 million Sunnis displaced inside of Syria or outside of Syria from their homes.

Of those 9 million displaced 2 million are displaced outside of Syria around the world.

All these things "Caused" ISIS to be exactly what it is.

IS ISIS evil?

ISIS is a reaction to grievous harm done to Sunnis in Syria and Iraq that got completely out of hand and now has to be dealt with like you would deal with a serial killer at this point.

Will the causes go away?

No. They will likely get worse over time. Stopping the effects of a cause doesn't negate the cause. So, even if we eliminate ISIS other possibly worse groups than ISIS will emerge because of the chaos and causes present after the last 4 years of the horror of war in Syria.