Short Answer: Technically, none of them completely. The “Injeel” is the revelation God gave to Jesus to deliver to people, but the gospels (Matthew, Mark, Luke, & John) were not written by eyewitnesses and do not, therefore, qualify as authentic recordings of his teachings. Paul, or Saul, was indeed an imposter and his writings are antithetical to the teachings of Jesus. The best way to know whether something you read in the New Testament is part of the original message God gave to Jesus is to ask yourself if it aligns with the core principles of Islam, chief among them being exclusive, absolute monotheism.
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The Four Canonical Gospels
The New Testament is the second part of the Christian Bible.
It is a collection of narratives, originally written by various writers in the Greek language of the first century.
It consists of 27 books, of which the first four speak of Jesus and his teachings, and were written “according to” Matthew, Mark, Luke and John.
These are the four canonical gospels, which according to the Christian historians were chosen from a collection of some eighty gospels extant in 325 C.E at Nicea and canonized by the Synod of Hippo.
It is claimed that the four canonical gospels are eyewitness accounts by the close disciples of Jesus; but this is not supported by evidence.
“…No one knows who actually wrote them. While they were eventually attributed to Matthew, Mark, Luke and John decades or centuries after they were written, educated Literalists admit that all four were, in fact, originally written anonymously. The startling fact is that none of our canonical gospels identify their respective authors (the “titles” of the “books” in our Bibles were added by editors long after the “books” themselves were written). In fact, the idea that the Gospels even represent eyewitness accounts arose decades, if not centuries, after they were written, when some later Christians in other countries came to view them as “memoirs of the apostles.” The gospels themselves, as we shall see, don’t claim to be eyewitness accounts or memoirs at all.” (Sean King, The Gospels Are NOT Eyewitness Accounts)
The Gospel of the Kingdom
The foregoing means that none of the four gospels can be called “the Gospel of the Kingdom” preached by Jesus.
See Matthew 4:23:
And Jesus went about all Galilee, teaching in their synagogues, and preaching the gospel of the kingdom, and healing all manner of sickness and all manner of disease among the people. (King James 2000 Bible)
It is unreasonable to suppose that Jesus was preaching one of the four gospels canonized by the Church three centuries later.
But it is quite reasonable to believe that the Gospel Jesus actually preached was a divinely revealed one.
Now the word Injeel used in the Qur’an is the Arabic version of the Greek word evangelion, meaning “good news”.
From the Muslim point of view, Injeel stands for the revelations of God received by Jesus, and nothing else.
We have no evidence that these revelations were faithfully recorded in Jesus’ time and passed on to the next generation.
What we now know as a “Gospel” is not ONE uncorrupted book of unquestioned authority, but any one of the four books of doubtful authenticity included in the New Testament.
Allah Almighty in His Noble Qur’an says:
And We caused Jesus, the son of Mary, to follow in the footsteps of those [earlier prophets], confirming the truth of whatever there still remained of the Torah; and We vouchsafed unto him the Gospel, wherein there was guidance and light, confirming the truth of whatever there still remained of the Torah, and as a guidance and admonition unto the God-conscious. (Qur’an 5:46)
The New Testament and the Injeel
As mentioned above, we do not find one book called the Gospel (or Injeel) among the books of the New Testament.
Instead we find four books called gospels, whose authorship and contents are of questionable authenticity, included in the New Testament along with a number of writings that often are at variance with the themes of these gospels themselves.
All the same, we may find a significant portion of the true Injeel in the four gospels of the present New Testament recorded as the sayings of Jesus.
Allah Almighty has commanded Muslims to believe in all His prophets and all the Books revealed to them.
Particularly He mentions the Books revealed to Moses and Jesus:
Step by step has He bestowed upon you (O Muhammad) from on high this divine writ, setting forth the truth which confirms whatever there still remains [of earlier revelations]: for it is He who has bestowed from on high the Torah and the Gospel. (Qur’an: 3:3)
Thus Muslims accept Jesus as one of the greatest prophets of God and the Book revealed to him, namely the Injeel as one of God’s revealed Book of Guidance.
Regarding Paul, or Saul, was indeed an imposter and his writings are antithetical to the teachings of Jesus.
How To Tell the Difference
Ultimately a Muslim can discern for himself or herself which parts of the current Gospels belong to the original injeel by asking this question: Does this teaching align with the principles of Islam?
Foremost among these is the concept of exclusive monotheism, or the belief that God is one, without partner and without sons.
If what one reads in the Gospels is in alignment with these principles, it’s safe to assume it’s part of the true message God revealed to Jesus, peace be upon him.
Otherwise, it was likely added at a later time.
And Allah knows best.