The Gospel of Barnabas is widely considered a pseudepigraphal work, likely written no earlier than the late medieval period. It should not be confused with the Epistle of Barnabas or other ancient Christian texts whose origins and manuscripts are well established. There are two known manuscripts of the Gospel of Barnabas: one in Italian, dated to the 16th century, and one in Spanish, dated to the 17th century. It is generally accepted that the original text was written in Italian and later translated into Spanish.

Scholars have noted that the Gospel of Barnabas exhibits clear literary dependence on medieval Italian works, most notably Dante’s Divine Comedy, as well as the Latin Vulgate Bible. Strikingly, despite the author's apparent intention to align the text with Islamic theology, the text demonstrates significant ignorance of both the Quran and foundational Islamic beliefs. For instance, unlike the Quran, which recognizes Jesus as the Messiah, the Gospel of Barnabas erroneously presents Mohammed as the true Messiah. The book also describes heaven as having nine layers, contradicting the Quran’s depiction of seven layers.

Beyond its theological inaccuracies, the text reveals historical anachronisms and geographical mistakes regarding 1st-century Israel. For example, it mistakenly claims that Pontius Pilate was the governor of Judea at the time of Jesus’ birth (Pilate only became governor around 26-36 A.D.), that Nazareth can be reached by boat (it is an inland town), and that Barnabas was one of the twelve apostles (he was not). Such glaring errors make it clear that the author lacked a deep understanding of both Islamic theology and the historical context of early Christianity.

For these reasons and more, the Gospel of Barnabas is dismissed by reputable scholars from all fields—Muslim, Christian, Jewish, and secular—as a late forgery. While pseudepigraphal writings were common in early Christian history, particularly from the 2nd century onwards, these earlier texts have been valuable for understanding their influence on Islamic scripture. In contrast, the Gospel of Barnabas is widely regarded as a tool of propaganda, used by some Muslim clerics to appeal to lay believers, rather than a text of genuine historical or theological significance.  The reason for the Muslim clerics utilization of this forgery is because the text denies the deity and crucifixion of Christ and because of its claim that after Christ, a prophet will come called Ahmad.