This question is applicable not just to the Injil, it also applies to other ancient scriptures like the Bhagavad Gita as well.
Not all parts of earlier scriptures have been corrupted and they have indeed retained some of their profound truths which could have come only from Almighty God Himself.
The great news is that Muslims have been given the Furqan i.e. the Criterion by which to filter out the corrupted segments of earlier scriptures from the profound truths that are undoubtedly found in them.
This Furqan is of course the noble Qur’an.
Think of the difference between earlier scriptures and the Qur’an in the following terms:
Which of the two water containers would you want to drink the water from?.. If you pick the second container, then you have indeed chosen to believe in the truth of the Qur’an.
I had just posted this comment below on an older thread before I came across this one. I think it’s just as appropriate here:
forums.catholic-questions.org/showthread.php?p=8379232#post8379232
To be a genuine Christian, whether Catholic, Orthodox or Protestant, one has to be convinced of that Jesus claimed his own Divinity, proven by his incarnation, life, miracles, death on the cross, resurrection, ascension, second coming. It doesn’t matter what group they belong to, when someone says they believe these things as fact, I know they are Christian fundamentally.
Christians know that if these things are not true, their faith is false. That is the truth we believe in (The person of Jesus is our “quran”) and Our witnesses as to that truth, our “prophets” and “messengers” are the apostles. Some of their witness, whether by their hand or the hand of their disciples, are written down in what we call the new Testament. We know that if they “the witnesses” were lying, our faith falls. We have a clear understanding of this…you see it’s simple reason.
I never met or spoke to Christ, I didn’t witness anything of his life at all. All I know about him, I’ve learned from the testimony of the Apostles, as handed down by our faith, written and preserved in our sacred tradition. That’s why Christian apologists, focus on the apostles, the corroborating evidence of their testimonies (as well as of the other Christian witnesses who were not apostles) from Jewish and pagan sources of their day, their very horrific martyrdoms as well as that of all who claimed to have witnessed Christ’s death and saw him resurrected etc etc. We understand the implications of the credibility or lack thereof of the primary witnesses. We are not scared of facing this truth and our apologists from the beginning have proven to be up to the task. This is the simple thing Muslims don’t get and what I believe the OP was asking on this thread.
No Muslim was witness to Islam’s “revelation” apart from Mohammed. No one saw Gabriel or spoke to him, or any of the other claims of Mohammed, his going to heaven, flight to Jerusalem etc, not even his closest companions or wives. All they ever witnessed was Mohammed giving them “recitations” little verses here and there on many different occasions over a 23 year period. “Recitations” that were handed to him by an entity nobody could verify in any way. If Mohammed lied about these experiences, Islam falls. Again, simple application of reason.
To be Christian, I must believe the apostles, to be convinced of the truth of Islam/quran, I must first believe Mohammed NOT the quran!! Unless I first believe Mohammed was exactly who he claimed to be, a “prophet”, a “messenger of Allah”, I have no reason to and cannot accept his supposed message-the Quran! The truth of the quran depends on the truth of Mohammed’s prophethood, NOT the other way around. If that remains unproven, the quran becomes nothing but a collection of stories, hymns, poems and prayers from 7th Century Arabia with multiple origins in Arabian Jewish and gnostic Christianity influences and several pagan Arabian sects, religions and customs.
Muslims must show that Mohammed was a prophet, not claim that the quran is its own miracle, as if this were a self evident truth like pointing to the sun and saying “I believe that is the sun”. Further, they cannot point to the quran’s teachings, like some do, to belief in one God. The quran has no copyright on this truth. It’s been taught even in African traditional religions, leave alone Judaism, Christianity, Zoroastrianism, ancient chinese religion etc. If it were exclusive to Islam, the matter would be simple. Demonstrating simply from reason that God is one, I’d have to join the religion that taught this. But since Islam simply adopted a belief that long preceded it, that’s no reason to become a muslim- Why not become a Jew or Zoroastrian? or just follow my own conscience and reason as to what is right? No, to chose Islam, I have to believe in Muhammed this is what distinguishes this faith from the others.
This is what the Jews recognized when they asked, very reasonably, for a sign that Mohammed was a prophet, earning thereafter his everlasting hatred when he could procure no such thing. In the OT when God gave messages to prophets that no one else witnessed, he confirmed the prophets with “miracles”. Again, simple reasoning. He gave a sign that everyone knew was beyond the claimed prophet, this was God’s own “witness” to that person’s claims. Mohammed expected the Jews to just accept his incredible claims, “just like that” like the Muslims had done and continue to do to the present age- To accept it just because Mohammed said it came from God-this and this alone is the whole basis for Islam as a religion- they believe in Mohammed’s claims, without any corroboration for them whatsoever- from anyone. That’s why criticizing him elicits more craziness than criticizing Allah himself.