John F. Kerry speaks during a press conference following an anti-Islamic State summit with the foreign ministers of 23 countries on Feb. 2 in Rome. (Nicholas Kamm/AFP/Getty Images)

The debate over what to call the Islamic State, the extremist organization that has created chaos in the Middle East over the past few years, is convoluted and controversial. In recent statements, however, Secretary of State John F. Kerry has made it even more so by labeling the group "apostates."

Kerry's repeated use of that word — a term to describe someone who renounces or abandons their religion — has raised many eyebrows. The Islamic State and other extremist groups justify their attacks on fellow Muslims by accusing them of apostasy — a crime that, they argue, is punishable by death.

Speaking to WorldViews on Monday, a State Department official suggested that Kerry was aware he misspoke when he used the word. "Secretary Kerry was simply trying to make a very strong case about the degree to which these terrorists do not represent Islam or the Muslim faith," said the official, who spoke on condition of anonymity in order to speak candidly. "He recognizes that the use of that particular word may not have been the best choice. The larger message is valid. That is that [Islamic State militants] do not act and certainly do not speak for vast majority of Muslims around the world."

Kerry has used the word apostate at least twice in public appearances: in December while speaking at a conference in Washington and last week while visiting Italy. “Daesh is in fact nothing more than a mixture of killers, of kidnappers, of criminals, of thugs, of adventurers, of smugglers and thieves,” Kerry said in Rome, using an Arabic acronym for the Islamic State. “And they are also above all apostates, people who have hijacked a great religion and lie about its real meaning and lie about its purpose and deceive people in order to fight for their purposes.”

A number of critics have lashed out at Kerry, a non-Muslim, for using a word with such heavy connotations in the Islamic world. On Twitter, Nasser Weddady, a popular online activist who grew up in Syria, was among those who chided Kerry for his use of the term, dubbing the secretary of state as a "takfiri" — a word used to describe a Sunni Muslim who accuses others of apostasy. Writing in the National Interest, Jacob Olidort of the Washington Institute for Near East Policy argued that Kerry's use of the word needlessly entangled him in a "nuanced theological debate — and not any obscure squabble, but a dispute that stands at the very center of the faith."

Kerry has been known for making similar statements that distance the group from the broader Islamic community. He has often referred to the group as Daesh, a word that the Islamic State is said to dislike because it is similar to another Arabic word meaning to trample or crush. While few doubt that the intentions behind this strategy are good, some have disputed the logic at work here. Writing for The Washington Post's Monkey Cage blog last year, Shadi Hamid and Will McCants argued that there was "something odd about an American president or Secretary of State opining on what is and isn’t legitimately Islamic."

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