Let us look at the history of prophethood. Let us see how this long chain began, how it gradually unfolded itself and finally culminated in the prophethood of the last of the Prophets, Muhammad (blessings of Allah and peace be upon him).
The human race began from one man: Adam. It was from him that the family of man grew and the human race multiplied. All human beings born in this world have descended from that earliest pair: Adam and Eve History and religion are agreed on this point.
Nor do scientific investigations into the origin of man show that originally different men came into being, simultaneously or at different points of time, in different parts of the world. Most scientists conjecture that one man would have been brought into existence first and the entire human race might have descended from that one man.
Adam, the first man on earth, was also the first Prophet of God. He revealed His religion — Islam — to him and told him to convey and communicate it to his descendents: to teach them that Allah is One, the Creator, the Sustainer of the world; that He is the Lord of the Universe and He alone should be worshipped and obeyed: that to Him they would have to return one day and to Him alone they should appeal for help: that they should live righteous lives in accordance with God's pleasure and that if they did so they would be blessed and if they did not they would suffer both here and in the hereafter.
Those of Adam's descendants who were good trod the right path, but those who were bad abandoned their father's teachings.
Some began to worship the sun, the moon and the stars; others took to the worship of trees, animals and rivers. Some believed that air, water, fire, health and all the blessings and forces of Nature were each under the control of a different god and that the favour of each one could be won by worship.
In this way ignorance gave rise to many forms of polytheism and idolatry, and scores of religions were formulated.
This was the age when Adam's progeny had spread over the globe, and formed different races and nations.
Every nation had created a different religion for itself, each with rituals of its own. God — the one Lord and Creator of mankind and the universe — was forgotten. Every kind of evil custom grew; many evils began to be considered right and many right things were either ignored or condemned as wrong. 
At this stage God began to raise Prophets among every people. Each one reminded his people of the lesson they had forgotten.
They put an end to idol-worship and the practice of associating other deities with God (shirk), did away with all customs of ignorance, taught them the right way of living in accordance with God's pleasure, and gave them laws to be followed and enforced in society. God's true Prophets were raised in every land and among every people. They all possessed one and the same religion — the religion of Islam.
No doubt the methods of teaching and the legal codes of different Prophets varied in accordance with the needs and the stage of culture of the people among whom they were raised.
The particular teachings of each Prophet were determined by the kind of evils, which he was trying to eradicate. When people were in the primitive stages of society, civilisation and intellectual development, their laws and regulations were simple; they were modified and improved as the society evolved and progressed.
Such differences were, however, only superficial. The fundamental teachings of all the religions were the same, i.e. belief in the unity of God adherence to a life of piety, goodness and peace, and belief in life after death with its just mechanism of reward and punishment.
Man's attitude towards God's Prophets has been strange. He has ill-treated them and refused to accept their teachings.
Some of the prophets were expelled from their lands; some were assassinated: some, faced with indifference, preached the whole of their lives without winning more than a few followers.
But despite the harassment, derision and indignity, to which they were perpetually subjected, these Apostles of God did not cease to spread their message. Their patient determination at last succeeded: large groups of people and nations were converted to their creed.
The false tendencies, born of centuries of deviation, ignorance and malpractice, now took another form.
Though they accepted their Prophets during their lives and practiced their teachings, after their deaths they introduced their own distorted ideas into their religions.
They adopted novel methods of worshipping God; some even took to the worship of their Prophets.
They made the Prophets the incarnations of God or the sons of God; some associated their Prophets with God in His Divinity.
In short, man's varied attitudes in this respect were a travesty of his reason and a mockery of himself; he made idols of those very persons whose holy mission was to smash idols.
By intermixing religion, rituals born of ignorance, baseless and false anecdotes and man-made laws, men so changed and perverted the teachings of the Prophets over the centuries that they became lost in a welter of fictions to the extent that it became impossible to distinguish the grain from the chaff.
Not content with this, they made up so many stories about their Prophets that real and reliable accounts of their lives became impossible to discern.
Despite all this, the work of the Prophets was not altogether in vain. Traces of truth survived. The idea of God and of life after death was assimilated in some form or other. A few principles of goodness, truthfulness and morality were accepted throughout the world. The prophets thus prepared the mental attitude of their respective peoples in such a way that a universal religion could be safely introduced — a religion which accords with the nature of man, which embodies all that, was good in all other creeds and societies, and which is acceptable to mankind.
As we have said above, in the beginning separate Prophets appeared among different nations or groups of people, and the teaching of each Prophet was meant specially and specifically for his people.
The reason was that at that stage of history, nations were so cut off from each other geographically that opportunities for mutual intercourse were non-existent. In such circumstances it was very difficult to propagate a common World Faith with an accompanying common system of law.
In addition, the ignorance of the early nations was so great that it had given different forms to their moral aberrations and distortions of Faith.
It was, therefore, necessary that different Prophets be raised to preach the Truth to them and win them over to God to gradually eradicate evils and aberrations; to root out ignorance and teach them the simple, pious and righteous life. God alone knows how many thousands of years were spent in thus educating man, and developing him mentally, morally and spiritually.
With the progress and spread of commerce, industry and the arts, intercourse was established between nations.
From China and Japan, as far as the distant lands of Europe and Africa, regular routes were opened both by sea and land.
Many people learnt the art of writing; knowledge spread. Ideas began to be communicated from one country to another and learning and scholarship began to be exchanged.
Great conquerors appeared, extended their conquests far and wide, established vast empires, and knit many different nations under one political system. Thus nations came closer and closer to one another, and their differences became less and less.
It became possible under these circumstances that one and the same faith, envisaging a comprehensive and all-embracing way of life, meeting the moral, spiritual, social, cultural, political, economic and other needs of men and embodying both religious and secular elements could be sent by God to the whole of mankind. More than two thousand years ago mankind had reached such a mental awareness that it seemed to be craving for a universal religion.
Buddhism, though it consisted only of a set of moral principles and was not a complete system of life emerged from India, and spread as far as Japan and Mongolia on one side, and Afghanistan and Bokhara on the other.
Its missionaries traveled far and wide in the world. A few centuries later, Christianity appeared.
Although the religion taught by Jesus Christ (peace be upon him) was pure Islam, his followers reduced it to a hotchpotch called Christianity, and even this overtly Israelised religion spread to far-off Persia and Asia Minor and to the distant climes of Europe and Africa. From these events it is evident that the conditions of mankind in that age demanded a common religion for the whole human race.
Indeed, when people found no complete and true religion in existence they began to develop existing religions, however defective, incomplete and unsatisfying they might have been.
At such a crucial stage of human civilisation, when the mind of man was itself craving for a world religion, a Prophet was raised in Arabia for the whole world and for all nations. The religion he was given to propagate was again Islam — but now in the form of a complete and fully-fledged system covering all aspects of the life of man. He was Muhammad, the Prophet of Islam (blessings of Allah and peace be upon him)!
Source: Towards Understanding Islam
 This is a very important and revolutionary concept. Its logical outcome is unity of mankind and the equality of human beings. It is stupid to distinguish and discriminate between men on grounds of class, colour, race or territory. In an age when nationalism, narrow racialism and bloodthirsty anti-semitism have torn the world into shreds, this creed of the unity of mankind is a powerful ray of hope for the future. – Editor.)
 This view of the history of religions is diametrically opposed to the so called evolutionary view of religion, which regards nature-worship as the first stage. More modern scientific studies are confirming the view that worship of one God (Tawhid) was the earliest Form of worship and all other forms are perversions of that original religion. Those who want to pursue the topic may refer to Prof. W. Schmidt's valuable research treatise. The Origin and Growth of Religions, English translation by H. J. Rose (London. Methuen). — Editor.)
There is a common misconception, mostly among Western writers, that Islam owes its origin to the Prophet Muhammad (blessings of Allah and peace be upon him) and some of the writers even go to the extent of calling him 'the founder of Islam'. This is a travesty of the truth. Islam has been the religion of all the Prophets of God and all of them have brought the same message from Him. Prophets have not been the founders of Islam: they have only been the messengers of it. Islam consists of the Divine Revelation conveyed to mankind by the truthful Prophets. — Editor.)
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