The Mihna (Inquisition, 833–848 AD): Caliph al-Ma’mun instituted a formal inquisition requiring scholars to affirm the Mutazilite position that the Quran is created. Those who refused were imprisoned. Ahmad ibn Hanbal refused, was flogged and imprisoned — his resistance made him the hero of Sunni traditionalism. The Mihna ended under Caliph al-Mutawakkil (~848 AD) who reversed policy, rehabilitated ibn Hanbal, and persecuted the Mutazilites. The Ashari synthesis subsequently became the Sunni mainstream.

The theological stakes: The Mutazilites argued the Quran must be created — an uncreated Quran co-eternal with God would be a second eternal being alongside God, compromising tawhid (divine unity). The traditionalists (Hanbalis, later Asharis) responded: the Quran is the speech of God (kalam Allah), and God’s speech is an eternal attribute of His essence — not a separate being but not created either. The Ashari solution: distinguish between God’s eternal speech-attribute (uncreated) and the ink, paper, and sounds used to express it (created). This preserves tawhid while affirming the Quran’s divine authority. The debate has direct implications: a created Quran could theoretically be subject to historical-critical reading; an uncreated Quran is absolutely authoritative and unchanging. This is why the stakes were high enough to justify an inquisition.