The Muslims world had expanded significantly during the Caliphates of the Rāshidūn, with having conquered Byzantine and Sassanid territories during the time of ʿUmar (رضي الله عنه), and entered North Africa and expanded further North into Azerbaijan during the reign of ʿUthmān (رضي الله عنه). The conquests had been carried out on quite large scales following their Caliphates. Muʿāwiyah (رضي الله عنه) was responsible for leading conquests that had expanded Muslim territories so span the Mediterranean, and the banner of expansion had been carried out by those who followed him, as al-Maʾmūn and al-Muʿtaṣim.

Expansion on such a scale, of course, would entail interacting with different cultures which, in turn, would lead to an exchange of ideas, followed by attempts at cultural and ideological syntheses. Translations, in addition, of Greek texts, were encouraged by leaders, and such led to the adoption of certain ideas and beliefs that were antithetical to Islāmic Orthodoxy. The ideas manifested in the greatest degree within two groups: the Muʿtazila and the Falāsifa, the former having especially been favored by Caliphs such as al-Maʾmūn and those following him, although he had sponsored some among the Falāsifa (al-Kindī, for example) as well to translate and to engage with Greek philosophical literature and discourses.

The Muʿtazila would not only spread their beliefs through debates and literature. As mentioned, they had earned the favors of the Caliphs and had earned prominent positions in their governments, which entailed their possession of political authority. Exploiting this privilege, they persecuted adherents to Orthodoxy en masse, and had the Caliph treat Muʿtazilism as a whole as the new Orthodoxy, and all other creedal forms, particularly those that affirmed and acknowledged the Attributes of God, instead of having negated them (as was the norm for the Muʿtazila and the Jahmiyyah), as heretical. There are reports of the Caliphs having sent deputies to households to confirm whether their residents espoused the Muʿtazilī creed, which had by then incorporated into Madāris curricula as well. Had it been discovered that a particular individual had not held Muʿtazilī beliefs, he would be punished. Such measures are what had led to the torture of Imām Aḥmad bin Ḥanbal, who had, in his conviction to uphold Orthodoxy, refused to give in to the demands of his torturers.

The Muʿtazila defended their doctrine rationally, using the tools that they had garnered with their studies of Greek Philosophy. A belief that has been defended rationally must itself be countered rationally if it is to be opposed. As such, there were Orthodox scholars who had engaged in debates with them for purposes of refutation, including Imām Abū Ḥanīfa himself. The theology of the Imām, however, was not formalized, and nor was the methodology he employed (kalām) held by any particular school.

During the second half of the 2^nd Century AH, there emerged a scholar by the name of Abū-l-Ḥasan al-Ashʿarī—whose lineage is traced back to the Companion Abū Mūsā al-Ashʿarī (رضي الله عنه)—who would utilize the same tools that the Muʿtazila had utilized to refute the doctrines of the Muʿtazila and uphold the Sunnah, and use the rational tools that were available to him to refute the doctrines that contradicted Orthodoxy.

The doctrine of another great Imām Abū Manṣūr al-Māturīdī began to gain prominence as well in the same period, his intentions being the same as those of al-Ashʿarī. While they had differences concerning certain ancillaries of the religion, with the doctrine of al-Ashʿarī being closer to that of the Ḥanbalīs and that of al-Māturīdī being closer to that of Abū Ḥanīfa, their schools both came to be the most conspicuous representatives of Islāmic Orthodoxy, given that nearly the entirety of the Shāfiʿī and Mālikī schools were adherents of Ashʿarism, while the same was the case for the Ḥanafīs and Māturīdism. (The Ḥanbalīs, as an overall school, adhered to the doctrine of Imām Aḥmad, although there were scholars who held to his fiqh but not to his creed.) Tāj al-Dīn al-Subkī summarizes the roles of the two Imāms well:

They did not innovate a novel opinion or develop a new doctrine, rather they only confirmed the doctrine of the Salaf and defended the way of the companions of the Prophet ﷺ. Ascription to him is only due to the fact that he was considered a spokesman for the way of the salaf and had held firmly to it and established proofs and evidence for it. The one who follows him in that and treads his path in proofs is called an Ashʿari…”¹

Al-Ḥāfiẓ al-Bayhaqī wrote, concerning al-Ashʿarī, “His elucidations strengthened what was not previously expounded upon from Ahl al-Sunnah and aided the beliefs of the past Imāms.” Al-Ḥāfiẓ Ibn ʿAsākir said,

We do not concede that he invented a fifth school. He only established the doctrines of the Ahl al-Sunnah that were made obscure by the innovators… Al-Ashʿari was tasked with refuting them (innovator groups) and was able to subdue them and expose their innovations.”²

Shaykh al-Islām ʿIzz al-Dīn bin ʿAbd al-Salām mentioned that their doctrines were unanimously agreed upon by the four madhāhib.³ Their eponymous schools continue to live to this day, and still constitute the majority of the Ahl al-Sunnah, and have exerted the greatest efforts towards countering groups that embraced and perpetuated innovations.⁴

References:

1. Ḥamad al-Sinān, Fawzī al-ʿAnjarī, “Ahl al-Sunna: The Ashʿarīs”, pp. 19-20, Sunni Publications.
2. Ibid.
3. Al-Ṭabaqāt, 3/65.
4. For further information regarding the subject matter, refer to Ahl al-Sunnah: The Ashʿarīs by Ḥamad al-Sinān and Fawzī al-ʿAnjarī. For information concerning differences between the Ashʿarīs and the Māturīdīs, one may consult The Differences between the Ashʿarīs and Māturīdīs by Ibn Kamāl Pāshā. For clarifications concerning doctrinal positions, or to eradicate misconceptions regarding such, one may also refer to G.F. Ḥaddād’s The Four Imāms and Their Schools.