This is a great question. The danger for all of us is that we can either ask it with a superficial answer already in our minds. “Of course Paul or one of the others corrupted it”, we can quickly answer without thinking too much about it, mostly because this is simply what we have heard. Or, we can think, “Of course not! What a silly idea”, again without really knowing why but mostly because we have been taught that way. This is the danger for all people who ask questions of sacred Books. We either dismiss it out-of-hand (because how we have been taught to think it not sacred) or we dismiss the question out-of-hand (again because of how we have been taught differently).
New Testament Writes other than Paul
With these considerations in mind I want to share my thinking and reasons on this question. Let us start with the writers aside from Paul. These writers were the disciples of Isa (PBUH) – his companions. They were the ones who followed him, listened to him, discussed with him, about the things that he did and said, both privately and in public. Some of them, such as John, Matthew and Peter were part of the inner circle of Isa’s 12 closest followers. They wrote eight of the books in the New Testament. Others, such as Mark, were among his wider circle of followers. The remaining authors (outside of Paul) were his brothers James and Jude. They grew up with Isa (PBUH) and James became the leader of the disciples in Jerusalem after the passing of Isa (PBUH) from this world. James, in fact, is mentioned in the Jewish historical writings of the 1st century AD. In that century there was a great Jewish military historian, Josephus, who wrote several books of history to the Roman Emperors of his day. In one of his books, writing of events in Jerusalem in the year 62 AD (32 years after the passing of Isa) he writes of how James, Isa’s brother, was martyred by his fellow Jews. Here is how he puts it:
“Ananus [the high priest] was rash and followed the Sadducees, who are heartless when they sit in judgment. Ananus thought that with Festus dead and Albinus still on the way, he would have the opportunity. Convening the judges of the Sanhedrin [the Jewish ruling council] he brought before them a man named James, the brother of Jesus who was called the Christ, and certain others. He accused them of having transgressed the law, and condemned them to be stoned to death” Josephus. 93 AD. Antiquities xx 197
Josephus is explaining that in 62 AD Ananus had just been made high priest in Jerusalem and there was a political confusion. Ananus used the opportunity to condemn James to death. His father (also called Ananus) had sentenced Isa (PBUH) to death about 30 years before and Ananus the son quickly took the opportunity to do the same with James. Thus James was a target for his years of leadership in Jerusalem with the followers of Isa al Masih (PBUH) his brother in Jerusalem.
What does the Qur’an say about these disciples of Isa (PBUH)?
So it is these men who wrote the books in the New Testament other than Paul’s books. To judge whether they corrupted the Injil we can first turn to the perspective given in the Qur’an. When I do that I find the following ayat:
When Jesus found Unbelief on their part He said: “Who will be My helpers to (the work of) God?” Said the disciples: “We are God’s helpers: We believe in God, and do thou bear witness that we are Muslims. Our Lord! we believe in what Thou hast revealed, and we follow the Apostle; then write us down among those who bear witness.” (Surat 3:52-53 – Al-Imran)
And behold I inspired the Disciples to have faith in me and mine messenger (Isa): they said, “We have faith, and you bear witness that we bow to Allah as Muslims (Surat 5:111 – Table Spread)
These ayat tell us quite plainly that the disciples of Isa (Jesus – PBUH) were a) Isa’s helpers, b) Allah’s helpers, c) and inspired by Allah to have faith in Isa. These disciples spoken of here in the Qur’an include none other than Matthew, Peter and John who wrote eight of the books in the New Testament, two of which are gospel books (Gospels of Matthew and John). And Mark, the disciple in the wider circle, wrote a third gospel. It would seem that if one believes in the Qur’an that one would also then have to accept the writings of these disciples. These writers certainly could not have corrupted the Injil. When we study the written gospels we are reading the writings of the disciples which are confirmed by the Qur’an. Paul did not write any Gospel account, rather he wrote sacred letters.
Now where I live in Canada few people readily believe that there are any books by Allah. Just because something is written in Qur’an or Bible (al kitab) does not mean that they would accept it. In fact they prefer secular historical sources because, in their eyes, they are less biased. But even from that point-of-view we have seen, from the writings of the historian Josephus quoted above, that there is a solid basis to accept the writings of James, and by extension, his other brother Jude.
So we find, whether from secular sources or from the Qur’an, logical reasons to accept the books of the New Testament that are not Paul’s.
The Witness of Isa (PBUH): the Taurat and Zabur are the first standards
But what about Isa himself? What did he give as the testimony we should accept? Notice where he appeals for a correct and uncorrupted witness to himself and his message.
Here we see that Isa PBUH (who is speaking) is using the Taurat (Book of Moses) to correct error among the experts in Jewish Law (Sharia)
“Now about the dead rising—have you not read in the Book of Moses, in the account of the burning bush, how God said to him, ‘I am the God of Abraham, the God of Isaac, and the God of Jacob’? He is not the God of the dead, but of the living. You are badly mistaken!” Mark 12:26-27
And here we see that Isa (PBUH) starts with Taurat and then continues with Zabur (‘Prophets and Psalms’) to teach about his role as the Masih.
He said to them, “How foolish you are, and how slow to believe all that the prophets have spoken! Did not the Messiah have to suffer these things and then enter his glory?” And beginning with Moses and all the Prophets, he explained to them what was said in all the Scriptures concerning himself. (Luke 24:25-27)…
He said to them, “This is what I told you while I was still with you: Everything must be fulfilled that is written about me in the Law of Moses, the Prophets and the Psalms.” Then he opened their minds so they could understand the Scriptures. (Luke 24:44-45)
And here we see that Isa again starts with Taurat (Moses’ writings) as the basis to judge the role of the Masih.
If you believed Moses, you would believe me, for he wrote about me. But since you do not believe what he wrote, how are you going to believe what I say?” (John 5: 46-47)
So we can see that Isa (PBUH) himself first appeals to Moses (which is the Taurat), then the Prophets and Psalms (which is the Zabur) to explain the role and purpose of the Masih. This is the reason I decided, both in my search, and now in this website, to start with the Taurat. If you look at the articles on the Signs of Adam, Cain&Abel, Noah, Lut, Ibrahim 1, 2, and 3 etc. you will see that the passages that support these articles all come from Taurat (and the Qur’an).
We are on safe ground if we start with the Taurat – Isa (PBUH) himself told us to. Here we are learning Signs that will help to unlock the mystery of the Injil. Then we will take what we have learned and compare it with the writings of the brothers and disciples of Isa – again staying on safe ground.
And what about Paul’s writings? What are we to make of them? Once we have studied the Taurat and Zabur and learned the Signs that Allah has definitely sent us, and then when we have studied the books of the disciples and brothers of Isa (PBUH) we knowledgeable enough so that if we turn to Paul we will notice if what he writes is different from what we have already studied. Without this background knowledge of the ‘safe books’ to inform us, it is impossible for us to really know if what Paul wrote is corrupted or not. But to keep our search on safe ground we will not start with Paul because his credentials are not unquestionable.
When I lived in Algeria I was surrounded by Arabic speakers and heard Arabic all the time. But because I did not know any Arabic I was not capable of deciding if what I heard was ‘correct’ Arabic or ‘corrupted’ Arabic. The limitation to make this judgment was in me – not the speakers around me. I did not have enough knowledge to be a good judge. A few years ago I took a course in Arabic. All people from all sorts of positions told me that the person giving this course spoke ‘correct’ Arabic. His reputation told me I could trust him as a ‘correct’ teacher. Starting from this course – that I knew was correct – I began to learn a bit of Arabic. Unfortunately I was not able to continue, but if I had, I could see that one day I could be in a position to decide if other people spoke ‘correct’ Arabic or ‘corrupted’ Arabic – because I would now have an informed basis from which to judge.
We are using exactly the same safe process to develop a solid understanding of the Signs of Allah, starting from which everybody says is ‘correct’ (Taurat), and then the disciples, to develop the basis to better judge if something else (like Paul) is corrupt or not. The danger for all seekers of the Straight Way is that we either accept too easily as revelation that which should be rejected, or that we discard too quickly the books that Allah intends that we learn from. Proceeding in this way, in humility and prayer before Allah, asking for His guidance, will make sure that we fall into neither error and thus stay on the Straight Path.