Throughout history, Allah has sent His messengers to many peoples. These messengers of Allah summoned mankind to the true path and communicated to them His ways. However today, some believe that the various messengers brought different religions to mankind. This is a misconception. The religions revealed by Allah to separate peoples in distinct periods were in fact one and the same. For instance, although the revelation given to the Prophet Jesus (as) abolished some of the prohibitions of the previous revelation, there are in principle no huge differences between the religions revealed by Allah. What has been revealed to the former prophets, the Prophets Moses (as) and the Prophet Jesus (as), and to the last Prophet Muhammad (saas) are essentially the single true religion in Allah's Sight. Verses of the Qur'an confirm this:
Say, "We believe in Allah and what has been sent down to us and what was sent down to Abraham, Ishmael and Isaac and Jacob and the Tribes, and what Moses and Jesus and all the prophets were given by their Lord. We do not differentiate between any of them. We are Muslims submitted to Him. If anyone desires anything other than Islam as a religion, it will not be accepted from him, and in the Hereafter he will be among the losers." (Surah Al 'Imran, 84-85)
These verses indicate that the right way revealed to man is Islam and that all the prophets summoned their peoples to a common way. In another verse Allah ordains: "... I am pleased with Islam as a religion (deen) for you!..." (Surat al-Ma'ida, 3) Allah sent His messengers to convey this religion, the one He is pleased with, to their peoples and thus warn mankind. Each person, to whom Allah's message is conveyed, and who is thus summoned to this religion is held responsible for adhering to it. However, some societies have accepted the message while others have denied it. In some societies, on the other hand, the right way has degenerated into perverted beliefs after the death of their messenger. This is related in the Qur'an as follows:
The Religion with Allah is Islam. Those given the Book only differed after knowledge had come to them, envying one another. As for those who reject Allah's Signs, Allah is swift at reckoning. (Surah Al 'Imran, 19)
One of the societies that went astray after following the right way for a while was a section of the Children of Israel (Bani Isra'il). As the Qur'an informs us, Allah sent many prophets to the Children of Israel and informed them about the right way. Yet, each time some of them revolted against a prophet or, after the death of a prophet, they transformed the right way into a set of perverted beliefs. Furthermore, from the Qur'an we know that even when the Prophet Moses (as) was still alive, some among the Children of Israel worshipped the golden calf during his short absence (See Surah Ta Ha: 83-94). After the death of the Prophet Moses (as), Allah sent many other prophets to the Children of Israel to warn them and the last of these prophets was the Prophet Jesus (as).
Throughout his life, the Prophet Jesus (as) called his people to live by the religion (deen) revealed by Allah and reminded them to be true slaves of Allah. He instructed them in the commandments of the Injil – the revelation granted to him, fragments of which may survive in parts of the Gospels. The Injil affirmed the commandments of the Tawrah – the revelation granted to the Prophet Moses (as), some of which remains in the Tawrah and in the Old Testament – which had by then been corrupted. Criticising the improper teachings of the rabbis who were responsible for the degeneration of the true religion (deen), the Prophet Jesus (as) abolished the false rules that were invented by some rabbis themselves and through which they derived personal gain. He summoned the Children of Israel to the unity of Allah, to truthfulness, and to virtuous conduct. The Qur'an tells us:
I come confirming the Tawrah I find already there, and to make lawful for you some of what was previously forbidden to you. I have brought you a sign from your Lord. So have fear of Allah and obey me. (Surah Al 'Imran, 50)
However, after the Prophet Jesus (as) left the earth, some of his later followers started to corrupt the revelation. Under the influence of some pagan ideas from the Greeks, they developed a perverted belief in the 'Trinity' (the Father, the Son and the Holy Ghost) (Surely Allah is beyond that). Under the name of Christianity, they adhered to a totally different religion. Although the Christianity of today contains some beliefs and practices belonging to the true faith, the religion revealed to the Prophet Jesus (as) has been corrupted by certain individuals who came after him. Many years after the first coming of the Prophet Jesus (as), unidentified people authored the books of what we know today as the New Testament, and they wrote them in Greek whereas the language of the Prophet Jesus (as) and his disciples was Aramaic, a language close to Arabic. In succeeding ages, historians compiled these writings. Consequently, Christianity today has lost much of the Prophet Jesus' (as) original teaching.
After the Prophet Jesus (as), Allah sent another messenger from a different tribe in order that through him He could reveal and restore the original religion to the world, and He endowed him with a noble book. This messenger was the Prophet Muhammad (saas) and the book is the Qur'an, the only unaltered Divine revelation. The Qur'an addresses all mankind and is relevant for all times. All people from all ages will be held responsible for adhering to this book, if they have been exposed to the message of Islam. They will be judged according to the Qur'an on the Day of Judgement. In this day and age especially, all the nations of the world are, in a sense, united and have almost become like a single tribe, thanks to technological breakthroughs. One academic referred to the world today as 'the global village'. Therefore, there are few people in the world today who can be unaware of the existence of the Qur'an and who are uninformed about Islam. Despite this, only a certain part of people has faith in the Qur'an.
It is glad tidings stated in the Qur'an and reported in detail in the hadith that the Prophet Jesus (as) will come back to earth and summon people to the right way so that the contradictory state of affairs that present-day Christians find themselves in will be resolved. As will be dealt with in succeeding chapters of this book, the Prophet Jesus (as) was raised up to the Presence of Allah and has not yet died a physical death. After a while, he will return and, as related in the hadith, make Islam prevail in the world together with Hazrat Mahdi (as). To the best of their abilities, both the Christian and the Muslim worlds are preparing to meet this blessed visitor and to merit his superior morality.