The Quran does not teach that every word in every earlier scripture vanished or became false. It teaches a more careful claim: God truly revealed the Torah and Gospel, some truth remained with their communities, but human handling of those scriptures made the Quran the final judge over them.
Why the objection sounds strong
The strongest version of the objection is this: the Quran repeatedly speaks respectfully of the Torah and the Gospel, says it "confirms" what came before it, and even addresses Jews and Christians as people who possess scripture. If Muslims then say the Bible is corrupted, are they not contradicting the Quran itself?
Several verses give the objection weight. For example:
And how do they come to you for judgment while they have the Torah, in which is the judgment of Allah?
Quran 5:43
And let the People of the Gospel judge by what Allah has revealed therein.
Quran 5:47
So a Muslim cannot honestly say, "The Quran treats previous revelation as worthless." It does not. It honors the original revelations given by Allah.
What the Quran actually criticizes
The Quran also says, in the same broad discussion, that some People of the Book altered, concealed, misread, or misrepresented revelation:
They distort words from their proper places and have forgotten a portion of that of which they were reminded.
Quran 5:13
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.
Quran 2:79
Among them is a group who twist their tongues with the Scripture so you may think it is from the Scripture, but it is not from the Scripture.
Quran 3:78
Classical scholars discussed this under the word tahrif. It can mean distortion of wording, and it can also mean distortion of meaning: mistranslation, selective quoting, hiding inconvenient passages, or interpreting a text against its intended meaning. The Quran mentions more than one form.
"Confirming" does not mean "endorsing every copy"
When the Quran says it confirms what came before it, it means it confirms the divine origin and remaining truth of earlier revelation, not that every manuscript, translation, canon decision, marginal note, and theological interpretation then in circulation was guaranteed intact.
The key verse is this:
And We have revealed to you the Book in truth, confirming what came before it of the Scripture and as a guardian over it.
Quran 5:48
The word "guardian" matters. The Quran is not merely one more book placed beside earlier texts. It is the criterion that preserves the truth, confirms what is true, and corrects what has been lost, altered, or misunderstood.
This also explains why the Prophet (PBUH) taught caution when hearing Biblical reports:
Do not believe the People of the Book and do not disbelieve them, but say, "We believe in Allah and what has been revealed to us."
Sahih al-Bukhari
That is a balanced rule. If a Biblical report agrees with the Quran and authentic Sunnah, Muslims may accept its meaning. If it contradicts them, Muslims reject it. If neither agreement nor contradiction is clear, Muslims do not build doctrine on it.
What this proves, and what it does not
This argument does prove that Muslims should not speak carelessly, as if the Quran denied all truth in the Bible. It did not. The Quran recognizes real revelation before Islam and acknowledges that the People of the Book possessed traces of it.
But it does not prove that the Quran endorses the Bible as fully preserved or religiously binding over Muslims. The same Quran that honors the Torah and Gospel also says people distorted words, concealed truth, and wrote things falsely in God's name.
So the Muslim position is not a contradiction. It is a distinction: the Torah and Gospel as revealed by Allah are true; the later scriptural inheritance contains truth mixed with human alteration; and the Quran stands as the final, protected measure by which the matter is judged.