From Bible Encyclopedia
bar-thol´ō̇-mū (Βαρθολομαῖος, Bartholomaíos, i.e. “son of Tolmai or Tolmai”):
One of the Twelve Apostles (Matthew 10:3; Mark 3:18; Luke 6:14; Acts 1:13). There is no further reference to him in the New Testament. According to the “Genealogies of the Twelve Apostles” (Budge, Contendings of the Apostles, II, 50) “Bartholomew was of the house of Naphtali. Now his name was formerly John, but our Lord changed it because of John the son of Zebedee, His beloved.” A “Gospel of Bartholomew” is mentioned by Hieronymus (Comm. Proem ad Matth.), and Gelasius gives the tradition that Bartholomew brought the Hebrew gospel of Matthew to India. In the “Preaching of Bartholomew in the Oasis” (compare Budge, II, 90) he is referred to as preaching probably in the oasis of Al Bahnâsâ, and according to the “Preaching of Andrew and Bartholomew” he labored among the Parthians (Budge, II, 183). The “Martyrdom of Bartholomew” states that he was placed in a sack and cast into the sea.
From the 9th century onward, Bartholomew has generally been identified with Nathanael, but this view has not been conclusively established. In the synoptic gospels Philip and Bartholomew are always mentioned together, while Nathanael is never mentioned; in the fourth gospel, on the other hand, Philip and Nathanael are similarly mentioned together, but nothing is said of Bartholomew. He was one of the disciples to whom our Lord appeared at the Sea of Tiberias after his resurrection (John 21:2). He was also a witness of the Ascension (Acts 1:4, Acts 1:12, Acts 1:13). He was an “Israelite indeed” (John 1:47).