Turkey is around 96% Muslim, yet it is a pretty secular state in terms of politics. There is no official state religion and the constitution provides for freedom of religion. Although it has changed a little over the years, separation of mosque and state has been a long tradition in Turkey going back to 1923.
ISIS absolutely despises this. It is totally at odds with their ideology, which claims that ISIS is a worldwide caliphate with sole authority over all Muslims worldwide. I would even guess that they hate Muslim nations which allow for freedom of religion even more than they hate Christians. ISIS was formed in 1999 as Jama’at al-Tawhid wal-Jihad (JTJ) in Jordan with the purpose of overthrowing the Kingdom of Jordan. Jordan is another place where freedom of religion has a long tradition and Jews and Christians largely live in peace next to their Muslim neighbors. As you can imagine, this infuriated JTJ, who considered the king to be an apostate. In all wars there is a special kind of hatred for those considered “traitors”, which is how Turkey and Jordan are viewed by ISIS.
thanks for your reply. I know Jordan is tolerant of other religions, but I thought Turkey was becoming less tolerant possibly wanting to turn the Hagia Sophia into a mosque rather than a museum. thanks for your explanation.