said: "If a man says to his brother, 'You are an infidel,' then one of them is right." Historian Bernard Lewis writes that in "religious polemic" of early Islamic times, it was common for one scholar to accuse another of apostasy, but attempts to bring an alleged apostate to justice (have them executed) were very rare. The tension between desire to cleanse Islam of heresy and fear of inaccurate takfir is suggested in the writings of some of the leading Islamic scholars. Al-Ghazali "is often credited with having persuaded theologians", in his Fayal al-tafriqa, "that takfir is not a fruitful path and that utmost caution is to taken in applying it", but in other writing, he made sure to condemn as beyond the pale of Islam "philosophers and Ismaili esotericists". Ibn Hazm and Ibn Taymiyyah also "warned against unbridled takfir" while takfiring "specific categories" of theological opponents as "unbelievers". Gilles Kepel writes that "used wrongly or unrestrainedly, this sanction would quickly lead to discord and sedition in the ranks of the faithful. Muslims might resort to mutually excommunicating one another and thus propel the Ummah to complete disaster." The Islamic State of Iraq and the Levant (ISIL), for example, takfired all those who opposed its policy of enslaving members of the Yazidi religion. According to one source, Jamileh Kadivar, the majority of the "27,947 terrorist deaths" ISIL has been responsible for (as of 2020) have been Muslims it regards "as kafir", as ISIL gives fighting alleged apostates a higher priority than fighting self-professed non-Muslims—Jews, Christians, Hindus, etc. An open letter to ISIL by 126 Islamic scholars includes as one of its points of opposition to ISIL: "It is forbidden in Islam to declare people non-Muslim unless he (or she) openly declares disbelief". There is general agreement among Muslims that the takfir and mass killings of alleged apostates perpetrated not only by ISIL but also by the Armed Islamic Group of Algeria and Abu Musab al-Zarqawi's jihadis were wrong, but there is less unanimity in other cases, such as what to do in a situation where self-professed Muslim(s) — post-modernist academic Nasr Abu Zayd or the Ahmadiyya movement — disagree with their accusers on an important doctrinal point. (Ahmadi quote a Muslim journalist, Abdul-Majeed Salik, claiming that, "all great and eminent Muslims in the history of Islam as well as all the sects in the Muslim world are considered to be