He addressed this theme in many of his writings, most notably in his renowned work, Iqtidā’ al-Ṣirāt al-Mustaqīm li-Mukhālafat Aṣḥāb al-Jaḥīm (The Requirement of the Straight Path to Differ from the People of Hellfire).

That book tackles a host of issues still vital to Muslims today, just as they were in his own time. Among them is the demonstration that the decisive proofs from the Qur’an, the Sunnah, and the consensus of the scholars jointly command us to differ from non-Muslims and forbid us from imitating them. He shows that such differentiation brings manifest benefits, whereas imitation yields equally manifest harms. The revealed texts and the statements of the early generations spell out the categories of people we have been ordered to differ from and prohibited from resembling: the People of the Scripture, the polytheists, the hypocrites, the folk of the pre-Islamic age of ignorance, the coarse Bedouins who have not acquired understanding of the religion, the foreigners—Persians and Romans—who neither embraced Islam nor adhered to its laws, and the people of sin, immorality, and corruption. All of these are upon a path of misguidance and deviation.

In this valuable work Shaykh al-Islam—may Allah have mercy on him—details a number of matters in which there is a stern prohibition against copying non-Muslims or following them in any respect, foremost among them the issue of festivals. He explains that Islam legislated only two yearly festivals for the Muslims: Eid al-Fitr and Eid al-Adha. It therefore emphatically forbids joining the disbelievers and the innovators in their festivals.

He likewise discusses other questions for which the revealed texts and the reports of the righteous predecessors prohibit following non-Muslims, such as constructing edifices over graves and turning them into places of worship; excess in veneration of the pious, including the building of shrines and pilgrimage sites; all other religious innovations; fascination with women; and factionalism in