|Zayd b. `Ali, the son of the fourth Shi`ite imam, Zayn al-`Abidin (PBUH), was a pious scholar who believed in the legitimacy of armed opposition and whose rising against the Umayyads in 122 AH resulted in his martyrdom. Zayd was joined in his campaign by a wide array of Shi`ites, as well as by such diverse groups as the Murji’ah and Muhakkimah. The general impetus to rise against the enfeebled Umayyad government resulted in the formation of a coalition of Shi`ite groups in Iraq – who in spite of divergences of views on creedal issues such as imamate and the caliphate of the Shaykhans – elected Zayd as their leader within the framework of a new religious sect which came to be known as Zaydism.
The paucity of material about the views held by Zayd together with the widely conflicting hadiths reported from him virtually preclude the determination of the degree to which he played a role in the formation of Zaydite beliefs. None the less, it may be concluded that he believed in the right of Imam `Ali (PBUH) to caliphate, while he did not consider the Shaykhayn as worthy of being condemned (bira’ah). In his teachings, he underscored the need to stand up to injustice and immorality and held that Imam Zayn al-`Abidin (PBUH) was obligated to rise up even if his followers barely exceeded three hundred. According to some reports, Zayd did not subscribe to the notion of the divinely appointed imam whose obedience was obligatory (muftarid al-ta`ah).
In the first hundred years of its existence, up to the early years of the 3rd century, the Zaydite movement went through a tumultuous phase, marked by a string of risings and political developments. During this period, the common view held by the various branches of the movement was that after the martyrdom of Imam Husayn (PBUH) imamate remained among his and Imam Husayn’s (PBUH) descendents – and according to some Zaydites among all the descendents of Imam `Ali (PBUH) – and that any one of them who initiated an armed uprising was the imam whose obedience became obligatory, without the notion of nass (the divine appointment) playing a role in his determination as imam. Among Zaydite factions the Jarudiyyah were closest in belief to the Shi`ites, since they rejected the right of the Shaykhayn to caliphate and drew a distinction between the knowledge of the Ahl al-Bayt (PBUT) and that of the rest of people. Others such as the Batriyyah and Sulaymaniyyah held views similar to those of the majority of Muslims in that they accepted the primacy of mafdul (the preferred) over afdal (the worthiest) as well as the imamate of the Shaykhayn. The former, however, came closest to the popular view, for they chose to suspend judgment on the issue of `Uthman’s caliphate. This was the reason behind the titles given to these two groups by the early Imamis, who dubbed the Batriyyah as “the strong” (aqwiya’) and the Sulaymaniyyah as “the feeble” (du`afa’) of the Zaydites. With regard to theological views held by the early Zaydites, reference may be made to the followers of Sabbah Mazni who believed in raj`ah. On the subject of the religious status of the committer of a kabirah, some early Zaydites, such as the Ibaddiyah, believed in the denial (kufr) of a blessing (ni`mah). There was deep disagreement among various Zadite groups on such fundamental issues as the divine attributes and justice as well as istita`ah (capacity, i.e. the power to act).
From the early parts of the 3rd century AH, the main branch of the Zaydites came to adopt a cohesive system of beliefs and the sectarian labels prevalent in the previous century, such as Jarudiyyah, came to be a thing of the past. The most influential Zaydite theologian of the period was Qasim Rasi (d. 246 AH) whose numerous works helped to reorient the movement from Imami views to that of Mu`tazilism. Yahya b. Husayn, known as the hadi ila ’l-lah (the one who guides towards God), was another Zaydite theologian who established a long standing imamate in Yemen in 283 AH and whose multitude of works consolidated the Mu`tazilte orientation of Zaydite theology.