Al-Sharīf al-Murtaḍā lived in the era of the great theologians

Al-Sharīf al-Murtaḍā lived in the time of the major theologians, and he was so audacious that he was willing to lay down foundational principles for Imāmī Shiʿism—both in the subtle and the manifest aspects of theology—that his own associates did not hold, so long as this enabled him to escape the objections raised by the theologians. Yet despite this, he would accuse his opponents of ignorance of the Imāmī creed. The truth is that the Imāmīs in the time of al-Murtaḍā and before him were themselves ignorant of what al-Murtaḍā innovated and attributed to them as a “school”! Indeed, some Imāmī scholars counted more than ninety principles in which al-Murtaḍā opposed his teacher al-Mufīd. Likewise, the researcher will observe even more instances in which al-Mufīd differed from his predecessors among the Qummīs. It is thus a thought and a doctrine fashioned by men and their opinions, independently of the Prophet’s household (the ʿitra).

The theologian Fakhr al-Rāzī perceived al-Sharīf al-Murtaḍā’s method and said:

“As for al-Murtaḍā’s claim that al-Naẓẓām, a group of Muʿtazilite shaykhs, al-Qāshānī, and the Imāmīs deny this and swear by God that they find neither knowledge nor conjecture (of it), we reply: the reporting of doctrines is not permissible on the basis of whim, oath-taking, or desire. Al-Naẓẓām did not deny this; rather, he conceded it, except that he said the consensus of the Companions is not a proof—according to what we previously related. The same applies to the statements of the rest of the Muʿtazilite shaykhs. As for the Imāmīs, the Akhbārīs among them—given that the great majority of the Shiʿa in ancient times were from among them—do not rely in the principles of religion, let alone its branches, on anything other than the reports they transmit from their Imams. As for the Uṣūlīs, Abū Jaʿfar al-Ṭūsī agreed with us on this matter. Thus none remain who deny knowledge except al-Murtaḍā along with a small number of his followers. It is therefore not far-fetched that such a group might agree upon obstinate denial of self-evident truths.”
(al-Maḥṣūl, 1/384)

So do not be deceived by the words of al-Murtaḍā or his teacher al-Mufīd—and others—when they say “the Imāmīs say” or attribute an opinion to the Imāmīs. Compound ignorance is to ascribe their statements directly to the Prophet’s household themselves.

Translation of Ustadh Kadhim Al Zaydi (May Allah reward him)