|As regards the formation of Imami theology, it may be concluded that apart from common beliefs held by all theological schools, e.g. tawhid (divine unity), the notion of imamate and its related subjects constituted the core of the issues discussed within Imami theological circles. Topics such as the reality of raj`ah (return, i.e. return to life, which will precede the universal resurrection) and the lawfulness of bida’ (innovation, i.e. a belief or practice for which there is no precedent in the time of the Holy Prophet (PBUH)) and taqiyyah (dissimulation, i.e. the precautionary dissimulation of one’s faith), in spite of their subsidiary nature, were among the subjects with which the Imami theologians were credited.
Compilation of books and treatises was a widespread practice among the Imamis. In fact, Imami theologians were the first to play a key role in the codification of the science of theology. In the 2nd and 3rd centuries AH, there existed a single branch of Imami theology whose major figures included Hisham b. Hakam, Yunus b. `Abd al-Rahman, `Ali b. Mansur, Abu Ja`far Sakkak and Fadl b. Shadhan. Among their earlier predecessors mention should be made of Muhammad b. `Ali (the author of al-Talaq) and Hisham b. Salim Jawaliqi who in all likelihood belonged to a single school of thought. Also included were Zararah b. A`yan and Abu Malik Hadrami who numbered among the eminent theologians of their day and who held particular views on subjects such as qadar. These theologians discussed a wide array of theological issues, especially tawhid, qadar and imamate, and some, like Hisham b. Hakam, dealt with exact topics such as huduth (creation) and qidam (pre-eternity).
Alongside these ancient theological schools, especially that of Hisham b. Hakam which lasted into the 3rd century AH, the two major and complex characters of the period were Abu `Isa al-Warraq and Ibn Rawandi, the outlines of whose intellectual development remain cloaked in mystery. The two came to adopt Shi`ite views for a short while, a fact that did not sit well with prominent Imami leaders. Towards the close of the 3rd century AH, the great Mu`tazilite leader Abu `Ali Jubba’i considered the schools of Hisham b. Hakam, Abu `Isa and Ibn Rawandi as the sole representatives of the Imami theological thought.
The later decades of the 3rd century AH marked a critical juncture in the development of Imami theology. The period witnessed the appearance of numerous works written by Imami theologians on the subject of imamate. However, the turning point came with the formation of the school founded by Nubakhti family, headed by the eminent Abu Sahl, who was instrumental in the formulation of a comprehensive theological system capable of standing up to the criticisms leveled by the opponents. The titles of his works indicate that apart form the issue of imamate he was in general agreement with Mu`tazilite positions.