Bible preserved (Quran)

Christian and Jelal discuss the Quran's view of the Bible.

Christian: Hi there, I wander if you have ever read the Injil (New Testament) before?
Jelal: As a Muslim, I believe that the Quran is the final revelation from Allah, and it supersedes all previous scriptures. You claim to have the Injil, but everyone knows that the original New Testament has been lost.
Christian: What makes you say that?
Jelal: Well, it’s clear in the Quran, it says again and again that the Bible was changed.
Christian: Really, I wonder could you show me in the Quran where it says that the Injil has been changed?
Jelal: Here you go, chapter 2:75, it says that there were those who, “used to hear the Word of Allah then change it knowingly after they understood it”. And then a few verses later, 2:79, mentions those “who write the ‘scripture’ with their own hands…”. It’s clear from the Quran, the Bible has been changed.
Christian: But do these verses mention the Tawrat, Zaboor or Injil by name?
Jelal: Well, no, they don’t...
Christian: Actually, there have always been those who try and distort the words of God. Even in Jesus day, the religious leaders would write down their own traditions claiming it was as authoritative as Scripture (see Mark 7). Jesus never accused them of changing the Bible, in fact he quoted from the Bible to rebuke them.
Jelal: Well, I guess that is possible.
Christian: And by the 7th Century, the Jews had written texts like the Talmud and many claiming to be Christian had also been writing many different texts like The Shepherd of Hermas. Maybe the Quran is talking about texts like these?
Jelal: I hadn’t thought about that…
Christian: The thing is, that whenever the Quran mentions the Christian Scriptures by name (e.g. Torah or Injil) it is always positive. Take Quran 5.46-47 for example. It says, “And let the People of the Gospel judge by what Allah has revealed therein. And whoever does not judge by what Allah has revealed - then it is those who are the defiantly disobedient.” How could Allah say that to Christians if they had corrupt Scriptures?
Jelal: Good point. But what about Quran 3.78, it says, “And indeed, there is among them a party who alter the Scripture with their tongues so you may think it is from the Scripture, but it is not from the Scripture. And they say, "This is from Allah," but it is not from Allah. And they speak untruth about Allah while they know.”
Christian: But again, what does this verse actually say? Does it say they changed the Bible text, or just that they were saying things that were different from the Bible?
Jelal: Well, I see what you are saying, maybe I need to look into this more…