Answer: Evidence reveals that the Gospel of Barnabas was most likely written by a fifteenth-century European who wrote inaccurately about the life of Jesus.

Beliefs about Jesus vary widely between Christians and Muslims because their sources differ. While Muslims often get their impression of Jesus from the Gospel of Barnabas, Christians trust the Gospels found in the Bible. Since the Gospel of Barnabas differs significantly from the Gospels of the Bible, one side must be false. Let’s first examine whether the Gospel of Barnabas is an accurate biography of Jesus.

The author: not Barnabas
The author of the Gospel of Barnabas could not have been the biblical Barnabas. The real Barnabas was a generous encourager of the early church (Acts 4:36-37). He was not one of the original twelve disciples of Jesus as the Gospel of Barnabas mistakenly claims. Barnabas was the one who persuaded the apostles that Paul had changed from a persecutor of the church to a follower of Jesus (Acts 9:27). The true Barnabas was a missionary, telling the good news of Jesus (Acts 13:2).

Date of authorship: the Middle Ages
If the Gospel of Barnabas were written in the first century, it would have been quoted in other documents of the same time period. It is not cited, however, a single time in works of either the church fathers or Muslim clerics until the fifteenth century. Those who claim the early authorship of the Gospel of Barnabas may be referring to the Epistle of Barnabas—a first-century book, though not divinely inspired.

A reading of the Gospel of Barnabas clearly shows that it was written neither in Jesus’ time nor shortly thereafter, as alleged. It contains far too many historical errors. The Gospel of Barnabas contains quotations from Dante Alighieri, references to an edict from Pope Boniface, and descriptions of feudalism. Therefore, scholars place the date of authorship around the fifteenth century.

Legitimacy: full of errors
The descriptions of Palestine show that the author of the Gospel of Barnabas was not familiar with its geography. He alleged that Jesus sailed to Nazareth—an inland city.

The Gospel of Barnabas says that Jesus was born when Pilate was governor, but history records Pilate becoming governor in A.D. 26 or 27—long after Jesus’ birth.

Trustworthy scholars have exposed the Gospel of Barnabas as a counterfeit. Therefore, it cannot be trusted as the biography of Jesus’ life.

What is the true story of Jesus?
If not the Gospel of Barnabas, where can you find the truth about Jesus? The Bible contains four Gospels that illustrate Christ from four divinely inspired perspectives. Evidence has consistently affirmed the Gospels as authentic and accurate.

Don’t be ashamed to read about the Lord Jesus. The Bible says, “So do not be ashamed to testify about our Lord, or ashamed of me his prisoner. But join with me in suffering for the gospel, by the power of God, who has saved us and called us to a holy life—not because of anything we have done but because of his own purpose and grace. This grace was given us in Christ Jesus before the beginning of time, but it has now been revealed through the appearing of our Savior, Christ Jesus, who has destroyed death and has brought life and immortality to light through the gospel” (2 Timothy 1:8-10; see also Romans 1:16-17).

For more information about the gospel of Barnabas, read this external link: http://answering-islam.org/Gilchrist/barnabas.html