Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him) said:
“Whoever thinks that these twelve are the ones who the Raafidis believe are their imams is utterly ignorant, for none of them carried a sword except ‘Ali ibn Abi Taalib. All the rest of the imams, apart from ‘Ali, never carried a sword, especially the Awaited One (al-Muntazar – the last imam). Rather he, according to those who believe in his imamate, is either scared and helpless or on the run, hiding for more than four hundred years.
This hidden one never guided anyone who had gone astray, he never enjoined any good, forbade any evil or supported any oppressed person; he never gave a fatwa concerning any issue, he never gave a ruling and it is not known that he even existed at all!
What benefit did he offer, even if he did exist, let alone Islam prevailing because of him?
Moreover, the Prophet (blessings and peace of Allah be upon him) stated that Islam would remain strong and this ummah would remain in good shape until there had been twelve caliphs. If what is meant thereby is these twelve imams, the last of whom is al-Muntazar, who supposedly exists now, until he appears to them, as they believe, then Islam should still have been strong during the Umayyad and ‘Abbasid periods, and it should have prevailed when the disbelievers emerged in the East and the West (i.e., the Mongols and the Crusaders) and did what they did to the Muslims, which would take too long to describe here. Islam should have been still prevailing until today, and this is something other than what the hadeeth indicates.
Moreover, Islam – according to the Imami Shi‘ah – is what they are following, and they are the most humiliated sect of the ummah. There are no followers of whims and desires who are more lowly than the Raafidis; no group is more concealing of their beliefs than them or more assidious in practicing taqiyyah (dissimulation). They claim to be followers of the twelve imams, yet they are the most humiliated. What support of Islam was achieved by these twelve, as they claim? Many of the Jews, when they became Muslim, became Shi‘ah, because they read in the Torah mention of twelve, so they think that these are the ones. But that is not the case; rather these twelve (in the hadeeth) are the men of Quraysh who took positions of leadership and caliphate in the ummah; at their time Islam was strong, and this is well known. End quote.
Minhaaj as-Sunnah, 8/173-174