In case you don’t want to read this long article, the answer is they want to kill everyone they consider an infidel. It’s that simple. Equally important to understand is that it’s not un-Islamic at all, rather it’s fully within the doctrines that all Muslims share. What sets them apart is their single-minded determination to fully carry out those doctrines and to bring about the apocalypse. We need to understand all of this before we can effectively counter them.