Christians claim that this gospel did not exist during the time of the apostles, their pupils, the church fathers or their pupils. Almost every book of the New Testament is mentioned and quoted in the writings of the early Christians but no reference whatever is made to the gospel of Barnabas. However, Muslims claim a long, colourful history for this manuscript going back to Irenaeus (130-200). For example Rahim says that Irenaeus "quoted extensively from the Gospel of Barnabas in support of his views. This shows that the Gospel of Barnabas was in circulation in the first and second centuries of Christianity". On examination one finds that Irenaeus in his writings quoted from the Epistle of Barnabas and not from what Rahim calls the Gospel of Barnabas. (An 'Epistle' is a letter and usually explains doctrine, while a 'Gospel' is an account of Jesus' life).
Rahim claimed that during Emperor Zeno's rule in 478, the remains of Barnabas were discovered, and a copy of the Gospel of Barnabas, written by his own hand, was found on his breast. According to him it is recorded in the Acta Sanctorium, Boland Junii, Tome II, pages 422-450, published in Antwerp in 1698 . However, the record actually says that a copy of the gospel according to Matthew, copied by Barnabas himself, written in his own hand, was found on his breast. This deliberate alteration of the record reflects little credit on Rahim's integrity. He omitted the words "according to Matthew, copied by Barnabas himself" and instead inserted "Gospel of Barnabas".
Evidence from Muslim History
Since the evidence from Christian history is sometimes rejected by some Muslims, we must also look at the evidence from Islamic history. The study of Muslim traditions and Muslim historical accounts suggest that Muhammad, the prophet of Islam, had good relations with the Christian ruler at Najran. At the time of Muhammad's birth, Arabs were in contact with Christians in Abyssinia, and also with the three major sections of the Church in the Middle East i.e. Byzantine, Nestorian and Jacobite-Monophysites. The Nestorians exercised the most influence over the Arabs. According to Ibn Ishaq, pictures of Mary and Jesus were to be seen on one of the Ka'ba walls ".
Muslim traditions tell us about various Christian delegations that came to visit Muhammad for discussion. On one occasion, a group of sixty people headed by Abd al-Masih, bishop of the Najran Christians, met Muhammad in the mosque at Madina to discuss the deity of Christ. Muhammad related to them that Jesus was not God. The incident is said to be recorded in the Qur'an (Surah 3:40-70). Here was an excellent opportunity to mention the gospel of Barnabas as evidence against the Christian' claim, if it was in existence, but not so. Neither did Allah reveal to Muhammad any verse with regard to it.
John of Damascus (d. 753), known as Yahya b. Mansur, the son of a civil servant who had been a treasurer to Caliph Muawiya and Abdul Malik, wrote on many subjects including the deity of Christ. Surely he would have also mentioned this gospel if it had been in existence then?
Bishop Timotheos (d. 823), whose term of office spans the high point of Abbasid power at Baghdad under Harun al-Rashid (786-809), held debates in the court of Khalifa Musa al-Hadi (785-6). Discussions were held not only in defence of what was held to be Islamic orthodoxy against free thinkers and heretics, but also about the four gospels. However, according to the transcripts, nobody mentioned the gospel of Barnabas. Muslim scholars debated the Godhead and the person of Jesus, yet they never mentioned this gospel. Caliph Jafar al-Mutawakal (847-861), who abolished the right of religion and the construction of churches and introduced discriminating laws against Christians and Jews , held debates in his court with people like Bishop Elijah. However, again, no one suggested the gospel of Barnabas as a reference.
The book Al-Fihrist of Abu al-Faraj Muhammad ibn Ishaq al-Nadim (935-990), which is claimed by Muslims to deal with every phase of medieval culture, has long lists of books and authors. He gives a list of all the books that are part of the Bible but nowhere mentions the gospel of Barnabas .
For several centuries Muslims ruled Spain (756-1492 CE) and there were many dialogues between Muslims and Christians, yet no Muslim ever presented this gospel as evidence against orthodox Christian belief. In this period there were Muslim writers, historians and philosopher like al-Farabi (d.950), al-Masudi (d. 956), al-Kindi (d. 961), Ibn Hazm (d. 1063), al-Ghazali (d.1111), Abu al-Abbas al-Arif (d. 1141); Ibn Rushd (d. 1198), Muhyi’l Din Ibn al-Arabi (d.1240), and Ibn Khaldun (d. 1406). However not one of them mentioned this document. Furthermore, in none of the commentaries on the Qur’an, prior to 1700 CE can any reference to this gospel be found. Therefore it is extremely difficult to believe that this gospel could possibly have been in existence before the fourteenth century, as discussed below.
Evidence from the document
The physical appearance of the manuscript of the Gospel of Barnabas in existence today suggests, in terms of its binding, the style of writing and its language, that it was written between 1500 and 1590.
Let us consider first the evidence within the text. In the Torah, God ordered the Israelites to observe a Jubilee year. "A Jubilee shall that fiftieth year be to you" (Leviticus. 25:11). However the gospel of Barnabas mentions this Jubilee but gives the interval of one hundred years (Barnabas, chapter 82). Where did the author get this figure from?
Around the year 1300, Pope Boniface VIII decreed the one hundred year interval for the church. In 1343, Pope Clemens VI changed it back to fifty years and later Pope Paul II (1464-1471) reduced it to twenty-five years. It would appear that the writer knew about the decree of Pope Boniface but thought it had been instituted by Jesus. This compels us to think that this gospel cannot be dated earlier than 1300 CE.
One finds several quotations of the writer Dante are attributed to Jesus in this gospel. For example, Dante's expression, "false and lying gods" in chapters 23, 78, 217 is not found in the Bible nor in the Qur'an, but shows up only in this gospel. The description of hell in this gospel is also remarkably similar to Dante's fantasy about hell, purgatory and paradise. In chapter 178, this gospel tells us that there are nine heavens, again reminiscent of Dante. It is interesting to note that Dante was an Italian who lived about the time of Boniface VIII. He started writing his famous "Divina Comedia" in 1300.
There are other medieval elements in this gospel. To mention just a few, in chapter 194, it is said that the family of Lazarus were overlords of two towns, Magdala and Bethany. Roman forces controlled most of the lands of Palestine in those days, so no such system of overlord rule was known. This is the kind of feudal rule which became common in the Middle Ages.
The reference to wine casks in chapter 152 is an obvious anachronism. The court procedures described in chapter 121 demand that the author would have had to be familiar with a medieval society. In the light of the preceding evidences and many other such evidences not listed here, both external and internal, it can be seen that this gospel must have been written by someone living many centuries after the Barnabas of the New Testament.