Barnabas was a hellenized Jew who joined the Jerusalem church soon after Christ's crucifixion, sold his property, and gave the proceeds to the community (Acts 4:36–37). He was one of the Cypriots who founded (Acts 11:19–20) the church in Antioch, where he preached. After he called Paul from Tarsus as his assistant (Acts 11:25), they undertook joint missionary activity (Acts 13–14) and then went to Jerusalem in 48. Shortly afterward, a serious conflict separated them, and Barnabas sailed to Cyprus (Acts 15:39). There is no contemporary mention of his subsequent activity, except for a brief reference by Paul a few years later (I Corinthians 9:6).

Nothing is known for certain about the time or circumstances of his death. Barnabas' alleged martyrdom and burial in Cyprus are described in the apocryphal Journeys and Martyrdom of Barnabas, a 5th-century forgery. Subsequent church tradition finds Barnabas in Alexandria, Egypt, and ascribes to him the Letter of Barnabas (an exegetical treatise on the use of the Old Testament) or pictures him in Rome and assumes that he wrote the Letters to the Hebrews. Barnabas' reputed tomb, discovered in 488, is near the Monastery of St. Barnabas, in the Cypriot city of Salamis, whose Christian community was founded by Paul and Barnabas.