Abu Hamid Muhammad al-Ghazali lived from 450/1058 to 505/1111, spanning a period in which the Sunni Abbasid order faced sustained pressure from the Isma'ili Fatimid caliphate in Cairo and its allied movements further east. He rose to prominence under the patronage of the Vizir Nizam al-Mulk, who secured his appointment to the chair of the Nizamiyyah madrasa in Baghdad, the most prestigious teaching post available to a Sunni scholar of the age. From this position al-Ghazali became a principal defender of Sunni orthodoxy, engaging in turn with the rationalist theology of the Mu'tazilah, the philosophical systems of Ibn Sina and al-Farabi, and the doctrine of authoritative teaching, Ta'lim, advanced by the Isma'ilis.

The Isma'ili challenge was not merely doctrinal. The Fatimids had held Egypt and North Africa since the early tenth century, and a Fatimid-aligned general briefly occupied Baghdad itself around the time of al-Ghazali's birth. Within al-Ghazali's own lifetime, an activist offshoot of the movement, later associated with Hasan-i Sabbah and the fortress of Alamut, adopted assassination as an instrument of religious and political struggle. On 14 October 1092, this group killed al-Ghazali's patron, Nizam al-Mulk. Al-Ghazali was urged by his remaining patrons, including the Caliph al-Mustazhir, to compose formal refutations of Isma'ili doctrine; the Mustazhiri was dedicated to the Caliph directly, and al-Ghazali was present at the oath of allegiance taken to him in February 1094.

In 1095, al-Ghazali underwent a personal crisis that led him to abandon his teaching post and withdraw from public life. Scholars have differed on the relationship between this crisis and the assassination of his patron three years earlier: some have argued that fear of the Isma'ilis was its direct cause, while others regard it as a more general reckoning with the foundations of his own theology, of which continuing concern over Isma'ili inroads among the Sunni population was one strand among several. Al-Qistas al-Mustaqim belongs to the body of work produced in the years following this withdrawal, and reflects both the polemical urgency of the Sunni-Isma'ili conflict and the more deliberate, method-driven theology al-Ghazali developed in his later career.

Al-Ghazali's output during and after this period included works of jurisprudence, philosophical critique, and mysticism, alongside continued polemic against the Isma'ilis, and he came to be honored as Hujjat al-Islam, the Proof of Islam. He died in 505/1111, leaving a body of work whose influence on Sunni theological method, and on the later reception of Islamic philosophy and mysticism alike, has remained continuous to the present day.