Shia and Sunni Muslims share much of the fundamental beliefs about Islam. The differences between the two Islamic groups stems, not from spiritual differences, but political differences. The differences between the two groups originate from the diverse positions and the practices in Islam that carry spiritual importance. The Sunni Muslims make up majority of the Muslim population in the whole world. Majority of the Shia population are only found in Iraq and Iran while in Yemen, Lebanon and Bahrain, the Shia Muslims are the minority. The two Muslim sects differ on the question of political leadership and this has affected certain aspects of their spiritual life. Despite the differences in religious practices and opinions, the two groups share various perspectives on Islamic beliefs and they consider themselves brethren in faith. This has resulted in the fact that they don’t claim membership of certain group but prefer themselves to be referred as Muslims.
Regarding the issue of leadership, Shia Muslims consider the Imam as sinless by nature and because he derives his authority from God, he is infallible. They venerate Imams as saints and only perform pilgrimage in their shrines and tombs to achieve divine intercession. Sunni Muslims, on the other hand, consider the fact that in Islam there is privileged class of religious leaders and there is no need of veneration or the intercession of saints; to them religious leadership is not birthright, but a trust that is bestowed upon an individual and can be taken away.
Shia Muslims consider the existence of animosity towards companions of Prophet Mohammed and the traditions they propagate. Shia Muslims do not subscribe to these opinions and traditions by the companions of Mohammed and they do not attach any religious premium to their testimonies. This is what differentiates the two groups in terms of religious practices like pilgrimage, prayer and fasting.
The differences between the two Muslims are traced to the time of death of Prophet Mohammed and the question of who will take over the Muslim leadership from him. Sunni Muslims are in agreement with the position taken by the prophet that new leaders should be elected from among prophet’s followers. Shia Muslims believe that leadership should be hereditary and hence they don’t recognize the significance of elected Muslim leaders. On the other hand, some Muslims share the belief that leadership should have stayed within the Prophet's own family, among those specifically appointed by him, or among Imams appointed by God Himself.
As opposed to the Sunni Muslims who perform prayers five times daily, Shia Muslims perform prayers thrice daily (morning, afternoon and evening); they also perform ritual ablutions before prayers. They also place a tiny clay tablet on where their forehead will touch during prayers. They also build monuments for their saints and they also organize pilgrimages to tombs of Imams. They consider death and martyrdom as the center of their devotion. Regarding law, Shia allows temporary marriage referred as Mutah; this is marriage legally contracted for certain period. Theologically, they both differ on the adoption of the principles of Mutazilite. Shia theology advocate for taqiya that implies dissimulation of individual beliefs. This allows believers to conceal their true beliefs for their own protection during persecution.
According to the teachings of Majid Khadduri, the origin of religious legitimacy in Islam is the word of God, derived from Koran and the divine wisdom of his followers (Sunna) and prophets. This includes the thoughts and actions of the prophet on daily religious issues. According to Khadduri, the prophet is the legitimate enforcer of God’s word. The prophets are the interpreters as well as the enforcers of the divine law of God. God is considered as the leader of Islamic community and his words are rules that guide human nature.