Allah, The Almighty, revealed the Quran to be His last, all-embracing Scripture containing the final manifestation of the Divine Law. This necessitates that it has to be safeguarded from the mischievous hands of men and from all corruption. This protection has been a reality from the time the Quran was revealed until today and will remain so forever. It contains no additions or deletions. It has reached us by so many chains of transmission that it is impossible for them to have conspired on a lie. It has been recorded and memorized innumerable times.
There has been no change in its text over time, not even in a single letter. Some of those who have committed it to memory cannot speak Arabic; nevertheless, they recite it exactly as it was revealed.
Allah has guaranteed the preservation of the Quranic text, as He, the Most Exalted, Says (what means): "Indeed, it is We who sent down the Quran and indeed, We will be its guardian." [Quran 15:9]
Allah also Says (what means): "And the word of your Lord has been fulfilled in truth and in justice. None can alter His words, and He is the All-Hearing, the All-Knowing." [Quran 6: 115]
As for the previous Scriptures, they were for a limited duration of time. Allah gave human beings the responsibility of preserving them, and they lost them through corruption, alteration, and concealment. Allah Says (what means):
"Indeed, We sent down the Torah, in which was guidance and light. The prophets who submitted [to Allah] judged by it for the Jews, as did the rabbis and scholars by that with which they were entrusted of the Scripture of Allah, and they were witnesses thereto." [Quran 5:44]
In the Quran, Allah Almighty informs us that the Torah was changed; He Says (what means):
"So woe to those who write the "scripture" with their own hands, then say, "This is from Allah," in order to exchange it for a small price. Woe to them for what their hands have written and woe to them for what they earn." [Quran 2:79]
Being the final, all-encompassing and preserved against any change, the Islamic Law abrogated all the previous Scriptures which sustained human interpolations. Abrogation generally takes place with regards to secondary matters of law. As for fundamental principles, like the Oneness of Allah, The Most Exalted, the prohibition of idolatry, and the fundamentals of worship – matters that form the basic call of all the Messengers, may Allah exalt their mention, they are not subject to abrogation.
The Law that came with Prophet 'Eesa (Jesus) abrogated part of the Law that came with Moosa (Moses) . Relating the words of Prophet 'Eesa to the Children of Israel, Almighty Allah Says (what means): "And I have come confirming that which was before me of the Torah and to make lawful to you part of what was forbidden to you…" [Quran 3:50]
The Islamic Law is lasting, remaining suitable for every place and time, and embracing the goodness of the previous manifestations of the Law. Allah Says (what means): “And We have revealed to you, [O Muhammad], the Book in truth, confirming that which preceded it of the Scripture and as a criterion over it." [Quran 5:48]
The Quran is different from the previous Scriptures in the following respects:
(1) The Quran is miraculous and inimitable. Nothing similar to it can be produced by human beings. Allah challenged both humans and jinn to produce the like of the Quran, as in the verse (which means): "Say, "If mankind and the jinn gathered in order to produce the like of this Quran, they could not produce the like of it, even if they were to each other assistants." [Quran 17:88]
He, The Almighty, further challenged the disbelievers among the Arabs to produce even one chapter similar to the Quranic chapters, Saying (what means): "And if you are in doubt about what We have sent down upon Our Servant [Muhammad], then produce a chapter the like thereof and call upon your witnesses other than Allah, if you should be truthful." [Quran 2:23]
(2) After the Quran, no more Scriptures will be revealed by Allah. Just as the Prophet Muhammad is the last Prophet, the Quran is the last Scripture.
(3) Allah has taken it upon Himself to protect the Quran from alteration, to safeguard it from corruption, and to preserve it from distortion (as stated in the meaning of [Quran 15:9] previously quoted. On the other hand, the previous Scriptures suffered alteration and distortion and did not remain in their originally revealed form (as mentioned above in [Quran 4:46]).
(4) The Quran, for one, confirms early Scriptures and, for another, is a trustworthy witness over them [Quran 5:48].
(5) The Quran abrogates them, meaning it cancels the rulings of the previous Scriptures and renders them inapplicable. The Law of the old Scriptures is no longer applicable; the previous rulings have been abrogated with the new Law of Islam.
Accordingly, Allah does not accept any religion except Islam as a way to His Pleasure, as He Says (what means):
"And whoever desires other than Islam as religion never will it be accepted from him, and he, in the Hereafter, will be among the losers." [Quran 3:85] - islamweb.net