What do the different imam doctrines of the Shia mean, such as belief in the seventh or the twelfth imam?

The Shia groups believe that the leadership of the believers is passed down in a line of imams from the family of the Holy Prophet (saw). They split over which son was the rightful successor at a certain point, and over whether the twelfth imam lives in concealment and will return.

In Shia Islam the imam holds a special position. He is regarded as the rightful leader of the believers, and many Shia Muslims believe that, like a prophet, he cannot err. According to their belief, the office passes from father to son within the family of the Holy Prophet Muhammad (saw). Besides the two main branches there are further subdivisions.

The first major split arose at the sixth imam. According to tradition the elder son was meant to inherit the office. The father, however, is said to have transferred it to the younger son because of doubts about the elder son's conduct. Some report that he later reversed this decision. Here the belief in infallibility becomes decisive. If an imam cannot err, his decision cannot have been wrong. So one group held fast to the first line, from which the Ismailis later emerged. The other followed the younger son.

The second split concerns the twelfth imam. One group believes that he did not die but went into concealment and will one day return. As long as he is alive, they hold, no one else can inherit the office, so the line ends with him. These are the Twelver Shia, today the largest Shia group, for example in Iran. Others believe instead that the office was passed on and continues to this day.

From the perspective of the Holy Qur’an a calm reflection is worthwhile. The second verse above shows that God made Abraham (as) a leader, but added that this promise does not extend to all his descendants. Leadership depends on righteousness, not merely on lineage. And where believers disagree, the first verse points to Allah and His Messenger (saw) as the standard.