"Sunnis Muslims make up about 85-90 percent of all Muslims worldwide, and Shi'a Muslims are the other 10-15 percent. Both sects accept Mohammed as the final prophet and both believe the Quran is the last revelation of Allah.
The division between the two groups began shortly after Mohammed’s death. The secular leadership of Islam, the Caliphate, was given to Abu Bakr, Mohammed's father-in-law, rather than to the person Mohammed had named as his successor, his son-in-law, 'Ali. The Muslims who supported 'Ali became known as the “Partisans of 'Ali” or Shi’a 'Ali, becoming shortened over time to Shi’a.
The Shi’a recognized as legitimate authorities only the successors to 'Ali, and to distinguish their recognized leaders from the secular Caliph of the Sunnis, they gave to their designated authority the title “Imam”, or spiritual leader of Islam."
'via Blog this' Read more Why there is a schism in Islam and what it means for Iran | Star-Exponent:
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