Every Muslim adult, as long as he is not a mujtahid, that is, one capable of deriving religious rulings from the Book of Allah and the Sunnah, is obligated to follow a religious authority who combines in him the requirements of knowledge, justice, piety, asceticism and the fear of Allah in accordance with the verse saying, "So ask the followers of the Reminder if you do not know" (Holy Qur'an, 16:43). 

If we research this subject, we will find out that Imamite Shi`as have kept up with the sequence of events, with no interruption in their chain of maraji` (religious authorities), since the demise of the Prophet and till our time. 

Shi`as continue to follow the Twelve Imams from Ahl al-Bayt, peace be upon them. The actual presence of these Imams continued for more than three centuries uninterruptedly without anyone of them contradicting the other in anything he said. This is due to the fact that the texts related to the Shari`a are always derived from the Book of Allah and the Sunnah. These have always been their reference. They followed neither analogy nor their own views. Had they done so, the disagreement among them would have become obvious to everyone as is the case with the followers of "Ahl al-Sunnah wal Jama`a." 

We conclude from the above that any sect of "Ahl al-Sunnah wal Jama`a," be it Hanafi, Maliki, Shafi`i, or Hanbali, is based on the views of one man who was distant from the time when the Message was revealed; he had no direct link with the Prophet at all. 

As for the sect of Imamite Shi`as, it is consecutive from the Twelve Imams who descended from the Prophet: the son quotes his father, and so on. One of them, namely Imam Ja`far al-Sadiq, says, "The hadith I narrate is that of my father and grandfather, and the hadith of my grandfather is the hadith of the Commander of the Faithful Ali ibn Abu Talib who quotes the Messenger of Allah, and the hadith of the Messenger of Messenger of Allah is that of Gabriel, peace be upon him, which is the speech of the Almighty." 

Then the chain of mujtahid faqihs started since then, and it has continued till our present time uninterruptedly. During each period, one or more marji` rises to distinction among the nation whom the Shi`as follow in their actions. This is done in accordance with the scholarly books of instruction (risalas) which each marji` derives from the Book of Allah and the Sunnah without expressing any personal views except in reference to issues related to modern times. Such views are relevant to modern scientific and technological progress such as heart or organ transplantation operations, artificial insemination, banking transactions, etc. 

One particular mujtahid may be distinguished with prominence over all the rest through the degree of his knowledge. Shi`as refer to such a mujtahid as al-marji` al-a`la, the supreme religious authority, or the head of the sect or of al-hawza al-`ilmiyya, the university-type circle of top scholars. This wins him the regard and respect of all other authorities. Across the centuries, Shi`as follow their contemporary faqih who undergoes whateverever problems other people undergo and is concerned about whatever concerns them, so they ask him and he provides them with the answers. 

Thus have the Shi`as in all ages maintained the two basic sources of Islamic Shari`a: the Book of Allah and the Sunnah, in addition to the texts transmitted by the Twelve Imams from the pure Progeny of the Prophet. Hence, their scholars feel no need at all to resort to analogy, or to express a personal viewpoint, because Shi`as have taken pains to record and safeguard the Prophet's Sunnah since the time of Ali ibn Abu Talib and will continue to do so till the Day of Judgment. The Imams from his offspring have been inheriting the same: son from father, and so on, treasuring such texts as people treasure their gold and silver. 

We have already quoted the statement of the Martyr Ayatullah Muhammad Baqir al-Sadr which he records in his own risala indicating that he does not rely except on the Holy Qur'an and Sunnah. Mentioning Martyr al-Sadr is only an example; all Shi`a authorities without any exception do the same. 

This brief research about the issue of religious following with regard to the Shari`a and religious authorities makes it clear for us that Imamite Shi`as are the ones who follow the Holy Qur'an and the Prophet's Sunnah as transmitted directly by Ali, the gate of the Prophet's knowledge, the divinely guided scholar and the nation's adviser after the Prophet and who, according to the Holy Qur'an, was created of the Prophet's soul.[121] 

So whoever comes to the city and enters through its gate will reach the pure fountainhead; he will take his fill and be fully refreshed. He will also have upheld the niche which shall never be untied because the Almighty says, "Enter the houses through their doors" (Holy Qur'an, 2:189). Whoever enters the houses anywhere other than through their doors will be called a burglar and will not be able to enter, nor will he come to know the Sunnah of the Prophet, and Allah will surely apprehend and penalize him for having thus transgressed.