The religion that God has prescribed to mankind is ‘ISLAM` (submission and obedience to God). It is only this religion that has the capacity to cover all the needs of man, and encompasses the above purpose. Therefore, the only recognized religion in the sight of God is Islam. “Truly the religion with Allah is Islam.” [3:19]
“And whoever seeks a religion other than Islam it will never be accepted of him and in the hereafter he will be one of the losers.” [3:85]
Because the religion of God (Islam) is guidance and truth, therefore it can lead man to his prosperity. “ He it is Who has sent His Messenger with guidance and the religion of truth.” [48:28]
In the history of religion it is the religions (plural) which are discussed by theologians. However, the holy Quran has never used the term religion in a plural form which indicates that the Almighty God recognizes only one religion and one path to Him and that is Islam. Such is one of the major differences between the prophets and the messengers of God in comparison to philosophers and thinkers - for even contemporary philosophers and thinkers oppose each other, and their doctrines and all schools of thoughts may contradict one another. That is not ever the case in the office of prophet-hood. There is only one Almighty God and one Law-Giver. He is the only source of authority of all prophets. The Almighty God never contradicts Himself and hence there shall not be any contradictions amongst the teachings of His messengers.
Nevertheless, the teachings of the prophets are similar to different grades of one school. For instance, the concept of mathematics that we learn in grade two does not contradict the mathematical concepts of grade one, nor does it contradict what we will learn in the ensuing grades. It will rather complete and advance mathematical knowledge until the student reaches a point whereat he has learned enough to be able to solve all new mathematical problems by utilizing his mathematical qualifications.
Such is the situation in the school of divine religion. The Almighty God considering the different levels of mentality of mankind throughout history, disclosed certain portions of the Truth to them until the entire Truth was disclosed to man by the revelation of the holy Quran to Prophet Muhammad (saww).