Undoubtedly, today, it would have been difficult to talk about pure Muhammedan Islam if it were not because of the Infallible Imams after termination of the Messenger's prophetic mission. A glance at 250 years of Imamate, i.e. from Imam Ali (A.S) until the Major Occultation of Imam Mahdi, shows that the Imams continued the line and mission of the Prophet (PBUH). In this regard, the Leader says:
"Imamate was to continue the mission of the Prophet (PBUH) for 250 years. The Infallible Imams did whatever the Prophet (PBUH) practiced and recommended during his prophetic mission. The Infallible Imams are generally responsible for creating Islamic society, i.e. a society based on Islamic law and principles, a society in which man finds a chance for his expected spiritual perfection."
The Infallible Imams did their best, each one in his time, to create such an Islamic society. Most of them did not accomplish their mission but laid the foundations for cultural and intellectual growth of their Shia followers and taught them how to fight heresy and deviation from Islamic law.
Today, the culture of the Infallible Imams, as the pure Islamic culture, is the richest, most meaningful, most genuine and purest religious culture. One dare say that many teachings of other Islamic sects come directly or indirectly from the endless treasure of wisdom and knowledge of the Infallible Imams.
Imam Baqir (A.S) says: "Truly and surely there is no right culture and sound word among people except those taken from us - the Infallible Imams." The Infallible Imams used to train ulema and scientists and promote Islamic science and wisdom on various occasions and diverse circumstances. Imam Sadiq (A.S) for instance, trained almost 4,000 scholars such as Jaber ibn Hayyan, father of chemistry.
The Imams lived in very hard conditions. One was under strict round-the-clock control, another was in jail, another one was forced to accept succession to the caliph, etc., but all of them continued promoting public awareness about Islamic law and training of scientists and ulema. Hereunder we will present the viewpoints of Imam Sadiq (A.S), the sixth Infallible Imam of the Shia Muslims and his fights against heresy and deviation from the Islamic law.
source : www.tebyan.net