The conception of Prophethood follows from the premises that it is the will of Allah that every human being should pursue a defined code of life and follow certain principles of conduct. Allah therefore had to send Prophets to acquaint the humanity with these principles and the code of life. The Qur’an says:
“We never chastise until We send forth a Messenger (to give warning).” (17:15)
The third Usul "Nubuwwat" calls for belief in all the Prophets sent by Allah from time to time for the guidance of humanity. According to Islam, Allah sent 1,24,000 Prophets in all. Adam was the first of them. Nuh (Noah), Ibrahim (Abraham), Musa (Moses) and ‘Isa (Jesus) were other prominent Prophets (peace be on them all). Our Prophet, Muhammad al-Mustafa (S.A.W.) was the last. Some Prophets came with a Shari'ah (code of life), while others merely propagated the Shari'ah of their fore-runners.
Since the words of a Prophet are to be obeyed and his actions are to serve as a guide, it follows that every Prophet should be Infallible in his thoughts, words and deeds.
According to Islam, the entire universe came into existence through the will of the Creator and was created with a definite purpose. The Holy Qur’an says:
“Indeed in the creation of the heavens and the earth and the alternation of night and day, are signs for the men of understanding heart, who standing and sitting and reclining bear Allah in mind and ponder on the creation of the heavens and Earth. “O our Lord!" say they, "Thou hast not created this in vain." (3:190-191)
And further the specific purpose of creation is:
“'I have not created the jinn and the human beings but for submission to me”. (51:56)
Now to explain this Divine will came the Divine Messengers known as the Prophets:
“Verily! Allah hath chosen Adam and Noah, the progeny of Abraham and the progeny of Imran above the worlds, the descendants one of the other. Allah is One Who hears and knows”. (2:33-34)
The Prophets never disagreed in fundamentals. Generally the Prophets were deputed for specified communities, regions or periods. Muhammad, the last of the Divine Messengers, was sent to express the will of Allah for the entire humanity, and for all times to come.
To quote, the Quran says:
“We have not sent thee but as a mercy unto all the worlds”. (21:107)
“And We did not send you except as a bearer of good news and warner to all mankind, but most people do not know”. (34:28)
“Say (unto them): ‘O mankind! I am Allah’s messenger to you all; Whose is the kingdom of the heavens and the earth! There is no God but He! He gives life and brings death! Therefore believe in Allah and His Messenger - the Makkan Prophet – who has faith in Allah and His words; and follow him so that you may be guided”. (7:158)
Islam therefore, is a perfect code of life for the entire humanity without distinction of classes, climes and countries. It lays first emphasis on the purification of the 'self’ of an individual based on the fundamental principles - belief in Oneness of Allah and in the life hereafter. This ultimately would lead to international brotherhood and creation of a peaceful society.