How did Isis come to be?

With all the talk of islamophobia I would really like to know how did Isis come to be? What are they basing their views on? Why are they yelling Allah Akbar and slaughtering people? I really just want to know how could a group so evil come out of religion? Something that's supposed to be a guidance for ones life and how could you kill anyone in the name of God? Is that what Mohamed would have wanted? If not then where are they going wrong? Tell me why I shouldn't be suspicious about a religion that seems to be tied to multiple terrorist groups? Tell me why?!!!! I really would love an answer! Thanks!! I saw someone post today some verses of violence in the Quran is that what is making them do all these horrible things?