In the Acts of the Apostles, Joseph Barsabbas (also known as Justus) is one of two candidates qualified to be chosen for the office of apostle after Judas Iscariot lost his apostleship when he betrayed Jesus and committed suicide. After the casting of lots he was not chosen, the lot instead favoring Matthias to be numbered with the remaining eleven apostles.
- 21 Wherefore of these men which have companied with us all the time that the Lord Jesus went in and out among us,
- 22 Beginning from the baptism of John, unto that same day that he was taken up from us, must one be ordained to be a witness with us of his resurrection.
- 23 And they appointed two, Joseph called Barsabas, who was surnamed Justus, and Matthias.
- 24 And they prayed, and said, Thou, Lord, which knowest the hearts of all [men], shew whether of these two thou hast chosen,
- 25 That he may take part of this ministry and apostleship, from which Judas by transgression fell, that he might go to his own place.
- 26 And they gave forth their lots; and the lot fell upon Matthias; and he was numbered with the eleven apostles.
—Acts 1:21–26 KJV
Both Joseph and Matthias had been followers of Jesus from the beginning of Jesus' public ministry after the baptism he received from John. He had continued as a member of the larger company of disciples even to the time that Jesus was taken up from them.
Further identification of Joseph is uncertain. In Christian tradition he is numbered among the Seventy disciples mentioned in Luke 10:1–24, although the biblical text mentions no names. "After these things the Lord appointed other seventy also, and sent them two and two before his face into every city and place, whither he himself would come." (10:1)
Theologian Robert Eisenman has read the shadowy figure of "Joseph Justus" as either a not-so-subtle cover for James the Just, or a cloned conflation who represents in a single figure all the Desposyni (Brothers of Jesus) —rejected, according to the author of Acts in favor of the otherwise-unknown Matthias.
In Christian tradition, this Justus went on to become Bishop of Eleutheropolis, where he died a martyr and is venerated as Saint Justus of Eleutheropolis. The location provides a date for this legend, since the site of Eleutheropolis was a mere village called Betaris in the 1st century, whose inhabitants were slain and enslaved with others by Vespasian in AD 68 (Josephus). The site was refounded, as Eleutheropolis, in AD 200 by Septimius Severus. The first historical bishop, Macrinus, can be found in the 4th century, when Eleutheropolis was an important city.