Paul referred to Barnabas in his First Epistle to the Corinthians and in his Epistle to the Galatians, in both cases implying that the recipients already knew of Barnabas. It is hardly possible that Paul would have written of Barnabas in this way, unless Barnabas was a real person. Barnabas is also mentioned in Colossians, but the clear majority of biblical scholars regard Colossians as pseudographical, so this epistle does not provide proof for Barnabas.

Acts made Paul a lesser character in the history of the early church, one who did not act on his own initiative but sought the authority of Peter and James on important matters. Whereas Paul had represented Barnabas as a loyal assistant, Acts had Barnabas become a mentor assigned to Paul by the Jerusalem elders in order to educate him and play a part in the Gentile church as an equal to Paul. There is no proof outside Acts that Barnabas was ever more than Paul's assistant.