This noble verse proves that falsehood in all its forms is excluded from the Book of God. This is because when exclusion is applied to the nature of a thing, it implies a general application. There is no doubt that alteration is one of the forms of false‌ hood, and accordingly, it should have no way to the Book of God.
Those who hold that alterations have occurred in the Quran respond to the above argument as follows:
The verses [Q. ٤١:٤١-٤٢] in question assert that the Book is divinely protected from inconsistencies in its ordinances, and deny that there is falsehood in what it says. To support this argument, those who held it resorted to the tradition related by Ali b. Ibrahim al-Qummi in his exegesis of the Quran, on the authority of the Imam al‌ Baqir (peace be upon him), who said [in an explanation of the protection verse], "No falsehood can come to it [the Quran] from the Torah, or the Gospels, or the Psalms, that preceded it, nor from that which follows it; that is, there will not be a book that will revoke it." Furthermore, they cite the tradition of the two Imams, al-Baqir and al-Sadiq, reported by al-Tabarsi in his Majma al-Bayan: "There is no falsehood in [the Quran] in what it reports about the past, nor in what it reports about the future."
The response to this argument is as follows:
The two traditions do not restrict falsehood to [misinformation and abrogation] only; thus, they do not contradict the broad applicability of the verse. This is particu‌ larly true when we take note of the traditions which convey that Quranic notions are not limited to specific objectives. We have already cited some of these traditions in the section dealing with the excellence of the Quran in the introduction. Undoubt‌ edly, the verse refers to the elimination of all sorts of falsehood from the Quran in all ages. Since alteration is one of the most obvious forms of falsehood, the Quran must therefore be immune from it. The proof that alteration is a form of falsehood that the verses deny in regard to the Quran is that [the first of them] describes the Book as "unassailable." Unassailability implies that the thing concerned is protected from change and loss. Had the word batil (falsehood) been specifically intended as inconsistency and untruth, it would not have been in harmony with describing the Book as unassailable.

Alteration and the Sunna

The third instance of proof is provided by the traditions about the "two things of high estimation" (al-thaqalayn), which the Prophet left among those in his community, saying that they shall not part until they meet him at the Pool [of al-Kawthar]. Ac‌ cordingly, he commanded tht community to adhere to both of these things, and these are the Book and the Family (al- itra). These traditions have been successively re‌ ported by both Sunni and Shiite chains of transmission. The proof deduced from these traditions regarding the absence of alteration in the Book of God is twofold: First, the belief in alteration necessarily means that it is no longer incumbent [on
the community] to adhere to the revealed Book, because it has been lost to the com‌ munity due to the alteration. However, the obligation to adhere to the Book remains until the Day of Resurrection, as the traditions about the "two things of high estima‌ tion"" indicate. Therefore. the belief in alteration is absolutely erroneous.