What was the main issue that drove Islam to split into two groups?Be sure to name the two groups.

The main issue that led to the split in Islam into two major groups was a disagreement over the rightful successor to Prophet Muhammad, who passed away in 632 CE. This disagreement eventually led to the division between Sunni and Shia Islam.

Sunni Islam:

- The majority of Muslims, approximately 85-90%, are Sunni. Sunni Muslims believe that the caliphs (successors) to Prophet Muhammad should be elected by the community. They recognize the first four caliphs – Abu Bakr, Umar, Uthman, and Ali – as rightful successors.

Shia Islam:

- Shia Muslims, representing about 10-15% of the Muslim population, believe that leadership should have remained within the Prophet Muhammad's family. They follow the lineage of Ali, who was the cousin and son-in-law of the Prophet, and they reject the legitimacy of the first three caliphs. The split was formalized with the assassination of Ali in 661 CE, leading to a separate line of leadership recognized by Shia Muslims.

The division between Sunni and Shia Islam, known as the Sunni-Shia or Shia-Sunni split, has historical roots in the early years of Islam and the differing views on the rightful leadership of the Muslim community. This schism has had profound implications for the development of Islamic theology, law, and political thought throughout history. It's important to note that the majority of Muslims coexist peacefully, and the division primarily involves theological and historical differences rather than fundamental disagreements in the core tenets of Islam.