The question is as to who was the most competent and...
The question is as to who was the most competent and eligible person to succeed the Prophet and to be the political and social leader of the Muslim ummah. The Shi'ah believe that Imam Ali was designated by Allah to this position. This question at present has only doctrinal and historical value, and not practical.
The second point is as to who are the authorities to whom the questions of religious law may be referred after the Holy Prophet; through what source do those authorities acquire their knowledge; and whether they are liable to err in giving their verdicts. As we know, the Shi'ah believe that all their Imams are infallible and this belief has a doctrinal as well as a practical value. The third aspect is ideological.
According to the Shi'ah belief in every age there has been a perfect man having a supernatural influence over the world and a sort of control on the hearts and the souls of men and on this account he is called Hujjat. The Qur'anic verse " The Prophet has more authority over the believers than that which they have over their selves ", is supposed to be referring to this sense of Wilayat as well.
Wilayat of Control or supernatural power does not mean, as some ignorant persons believe, that any human being can acquire the power of running the affairs of the universe and carrying out the functions of creating, sustaining, giving life and causing death on behalf of Allah. Allah has organized the order of the universe on the basis of a system of cause and effect.
Though the beings called angels have been described as " governors of the events " (al-Nazi'at, 79:5) and " distributors of the affairs " (al-Zariyat, 51:4), this aspect is not in any way inconsistent with the principle of the Unity of Allah and His having no associate or partner as Creator and true Owner. No one is Allah's Waly in the sense of being His helper, assistant or even His tool.
The Qur'an says: " He has no partner in the Sovereignty nor has He any protecting friend because of weakness. Magnify Him with all magnifcence ". (Surah Bani Israel, 17:111). The relationship of the Creator and the created is only that of creation, sustenance and non-entity. The Holy Qur'an describes Allah as fully Independent. But while it says, for example; " Allah takes the souls (of men) at the time of their death ".
(al-Zumar 39:42), it also says: " Say: The angel of death is given charge of causing you to die; then to your Lord you will be returned ". (al-Sajdah 41: 11).