Only the radical Muslims or extremists who participate or support ISIS think that ISIS is doing their violent acts in accordance with their religion. However, there is another group of Muslims that make up the true meaning of Islam. They are against ISIS but they are still Muslims. Unfortunately, people around the world do not view the separation of these Muslims, but instead think that all Muslims are terrorists which are not true.
Actually, a small part of the group are actually a part of ISIS because the rest are true followers of Islam. In all religions, there are bad people who misinterpret or they interpret their holy book the way that they want to. These people only claim to be a part of a religion, but they really are not.