The Quran does affirm that Allah gave Jesus an actual revelation called the Injil. But it does not claim that a bound manuscript, written in Jesus's own hand or preserved unchanged in a known archive, survived until the seventh century.
What the objection gets right
The historical challenge is serious if the claim is framed this way: Jesus possessed a complete book called the Gospel, Christians preserved it as an identifiable document, and the Quran later confirmed that document word for word. No such manuscript has been found, and the earliest surviving Christian writings are not a single independent "Gospel of Jesus" matching that description.
That would be a genuine difficulty. But it is not the claim the Quran makes. It is a stronger claim supplied by the objection itself.
What the Quran actually says
He has sent down upon you the Book in truth, confirming what came before it. And He revealed the Torah and the Gospel.
Quran 3:3
And We sent, following in their footsteps, Jesus son of Mary, confirming the Torah that came before him. And We gave him the Gospel, in which was guidance and light.
Quran 5:46
Here the Injil is a revelation given by Allah to Jesus. The Quran calls revelations "books" even when it does not describe their physical format, copying history, or later transmission. Thus "book" need not mean a surviving codex with a known chain of manuscripts. Jesus may have taught the revelation orally, written material may have existed, or both. The Quran does not settle that historical detail.
Nor does "confirm" mean that the Quran endorses every later document bearing a related name. It confirms the divine origin and genuine guidance of the earlier revelation, while also correcting disputes and judging what remains of it. The Quran describes itself as confirming previous scripture and as a criterion over it in the same passage:
And We have revealed to you the Book in truth, confirming what was before it and as a criterion over it.
Quran 5:48
What Muslims are required to believe
Belief in the revealed books means affirming that Allah truly revealed the Torah, the Injil, and other scriptures to His messengers. It does not require claiming that every original manuscript remains available, or that present religious communities preserved every word without alteration. Classical Muslim scholarship distinguished the original revelation from later transmission, interpretation, and textual changes.
When the Quran tells the people of the Gospel to judge by what Allah revealed in it, it refers to the genuine guidance still present among them, while exposing their failure to follow it fully. It is not a blanket declaration that every later Christian text is identical to the Injil given to Jesus.
So the evidence does not establish that the Injil was a fictional "phantom book." It does establish that no independently identifiable original Injil is presently available. Islam already allows for that distinction: the revelation was real, its complete original form is not required to survive, and the Quran is the final accessible criterion by which earlier claims are judged.