The religion of Shiism is based on five fundamental principles (Usool) while Islam is based on three Usool. Usool (the Roots) refer to those fundamental doctrines which constitute the foundations of Deen. In the unanimous opinion of all – both Shiahs and Sunnis — rejection of anyone of the Usool constitutes kufr. Any person who denies any one of the Usool is termed a Kaafir (unbeliever) according to both the Shiahs and Sunnis. The five Usools according to Shiism are: Tauheed, (belief in the Unity of
Allah Taala), Risaalat or Nubuwwat (Belief in the Ambiyaa), Imaamat (Belief in the Imaams), Adal (Belief in the doctrine of compulsory justice – that Allah Taala is compelled to act in accordance with justice as understood by the Shiah religion), and Aakhirah. According to Islam, the three Usool of Deen are Tauheed, Risaalat and Aakhirah.
The widely divergent paths and attitudes between the Shiahs and the Sunnis can be well understood when this great disparity in the fundamental basis in their respective religions is studied. Since the Sunnis reject two of the Shiah roots as being utterly baseless and concoctions, it is clear that all Sunnis in terms of the Shiah religion are Kaafir.
This fact is explicitly proclaimed by Shiah authorities. Of the five fundamental principles of the Shiah religion, the doctrine of Imaamat is considered of greater importance than Rislaalat. Thus the Shiah religion accords greater importance and greater rank to those whom it regards as its Imaams. Some Shii references will be cited here to indicate the high rank and vital importance which Shiahs bestow to their Imaams. In fact, the importance Shiahs accord to their Imaams eclipses the ranks of the Ambiyaa. In the Shii book of theology, Usoolul Kaafi of Kulaini, the following teachings of Shiism are recorded regarding the doctrine of Imaamat: « The Hujjat (Proof) of Allah is not established over His creation without the medium of an Imaam from whom the inner knowledge of Allah is acquired. « If the earth remains without an Imaam it will be annihilated. « If the Imaam is removed from earth for even a moment, it (the earth) will churn with its inhabitants like the ocean churns with its waves. « A man cannot be a believer unless he recognises Allah, His Rasool, all the Imaams and the Imaam of his age. « Whoever denies the Imaam is like a person who denies the recognition of Allah and His Rasool. « Whoever recognises (accepts and acknowledges) us (the Imaams) is a Mummin and whoever denies us is a Kaafir.
« Obedience to the Imaams is Fardh (compulsory) like the obedience to the Rasools.
« The Imaams possess all the knowledge which was bestowed to the Malaaikah, the Ambiyaa and the Rusul.
« Allah Taala has a special kind of knowledge from which He bestows to the Imaams exclusively. « When Allah Taala commences with anything of His special type of knowledge, He presents it to the Imaams.
« The entire earth belongs to the Imaam.
« The entire earth and the Hereafter belong to the Imaam. He places it as he pleases and gives it to whomever he pleases.
The differences between Islam and Shiism are numerous and wide. A study of Shiism will conclusively establish that the type of reconciliation between Islam and Shi`ism called for by those who are not versed in the Shariah, is quite impossible. The difference on just this one issue of Imaamat is so vast and extreme that the gap between the two groups – Shiahs and Sunnis – can never be bridged. The Sunnis follow the Path of Rasulullah (sallallahu alayhi wasallam) and his Sahaabah, while the Shiahs are astray plodding the path of baatil and kufr. The only way in which Islam can reconcile with those who have gone astray is by their renunciation of dhalaal (error and deviation) and kufr. There is no other way.