Divine injunctions: Relationship between the Qur'an and the pervious scriptures

A traveler does not need to turn to stars for direction in broad daylight. Similarly, after the revelation of the Holy Qur'an Muslims abandoned seeking guidance from the previous scriptures since they are an amalgam of truth and falsehood.
However, the previous scriptures rival the Holy Qur'an in that the latter is one of God's revelations and the prophet who brought it is also a member of the community of the prophets and messengers of God. All Muslims, from Adam to us, in spite of the great number of the prophets sent in different times and regions, are one ummah following a single religion. This makes it imperative for us to know the teachings of the earlier books. A study of these books can afford us a great variety of benefits.
It will help us appreciate the excellence of the Holy Qur'an over the previous scriptures which in turn will lead us to thank God for blessing us with the unparalleled Book. It will also help us discern the points lost upon commentators of the later generations which in turn made it impossible for them to get to the true purport of certain Qur'anic passages. This will also avail us with sound proofs to establish arguments against the People of the Book. This last point alone is a great benefit.
With the earlier scriptures already present, the Holy Qur'an was revealed to serve two basic purposes. First, parts of religion which were not yet revealed in those books were revealed.
Second, it clarified the matters which were forgotten by the earlier communities. Many matters were disputed among them and the Holy Qur'an decided these differences.
Some of the matters did not remain clear to them and they lost the right course. The Holy Qur'an revealed the true nature of such matters. Most importantly, they had manipulated and adulterated many parts of the divine revelation. The Holy Qur'an corrected such things. The Almighty says:
Then woe be to those who write the book with their own hands and then claim that it is from God in order to earn some trivial benefit!(2:79)
These are the basic reasons which called for a fresh divine revelation. Besides fulfilling these purposes, the Holy Qur'an helps us remember God, propagate His teachings and disseminate His message which are characteristics common to all the divine revelations.
Since the Holy Qur'an was revealed to fulfil a specific purpose, it does not but discuss teachings of the highest value. It has left out the details of narratives, dispensable explanations of divine commandments and events of micro-history. The general addressees of the Holy Qur'an were fully aware of these things.
Repeating such things would have been futile and wearisome for such an audience. Therefore, the historical narratives the Holy Qur'an discusses have been put very cogently either in order to provide precedence or a historical allusion (talmih) or to unveil any hideous cheating by the People of the Book. Similarly, it has also not dealt with the well-known religious practices the humans were obligated to carry out except for explicating those aspects which still needed completion and perfection.
The believers in the call of the Holy Prophet (sws) had either been the People of the Book or those who had intermingled with them. The latter category too was, owing to their acquaintance with the former, aware of the teachings of the earlier books.
They did not find it difficult to understand the Qur'anic passages which only alluded to the things mentioned in the earlier books leaving out certain details. They noticed the gulf of difference between the Qur'anic style of expression and the earlier books in spite of the unity of purport and this raised the status of the Holy Qur'an in their eyes. Regarding such audience of the Holy Qur'an, the Almighty says:
And when they listen to what has been revealed to the Prophet, you see their eyes fill with tears as they recognise its truth. They spontaneously say: "Lord! We believe. Count us among the witnesses."(5:83)
THE ABOVE DISCUSSION LEADS TO THE FOLLOWING CONCLUSIONS:
a) Errors in the earlier scriptures should be determined in the light of Holy Qur'an. Difficulties in deciphering the meaning of their complex passages should also be explained in the light of the last revelation. The only way for the People of the Book to get to the truth is to follow the last revelation of God.
b) Since the Holy Qur'an is a completely authentic and secure word of God, it will serve as the final word where the earlier books differ with it on certain historical facts.
c) Those having full exposure to the history of divine revelation, starting from the first prophet to the last, and thus having a clear understanding of the gradual divulgence of the shari 'ah of God to mankind, will certainly be able to see clearly the excellence of the Muslim ummah.
d) The contradictory isra iliyyat, which are an amalgam of truth and falsehood, will be explained away. Those of us who have been on error because of such narratives will see the light.
e) The People of the Book will be able to learn that the Holy Qur'an does not draw upon these books rather it removes errors found in them and guides them out of the labyrinths of assumptions and conjectures to the right path.
f) Many of the Qur'anic verses which refer to the torah but the Muslim scholars take them to be referring to the Holy Qur'an will be correctly understood.
THE FOLLOWING TWO VERSES ARE EXAMPLES:
Any verse which We annul or consign to oblivion We replace with a better or a similar one. (2:106)
And every prophet or messenger that we sent before you, whenever desired something, Satan interpolated with his desires. But God cancels the whispers of Satan and establishes his commands firm. (22:52)
Before concluding this discussion, I want to discuss a point which the Christians usually put before Muslims in order to deceive them, dubbing it as the most manifest argument against Muslim's stance.
They maintain that the Holy Qur'an at one place clearly requires from the Muslims that they believe in the Gospels. Granted this, they say, the Holy Qur'an contradicts itself when, on any other occasion, it negates any of the evangelical statement, something it often does. This, they assume, provides them with an opportunity to invite the Muslims to have faith in whatever falsehood they have inserted in their book. In this effort, they usually present proofs from the Qur'anic verses.
- Courtesy Renaissance