Q. Why do we call Paul an apostle when he was not part of the Twelve Apostles, following Jesus around Galilee?
A. Here’s a reply from Father Reginald Martin:
St. Luke tells us Jesus “called his disciples to himself, and from them he chose Twelve, whom he also named apostles” (Lk 6:13). This would appear to be a very exclusive group, but a close examination of the names suggests the matter is somewhat less tidy, as the Evangelists identify three individuals named James, and another three named Judas. In addition, the Acts of the Apostles refers to “brothers” of Jesus in the Upper Room with the apostles at Pentecost (see Act 1:13-14). Thus although the first rank of apostles may, indeed, have numbered only twelve, those who might claim the title were probably more.
Peter addresses those in the Upper Room and says apostles must have been among Jesus’ disciples “from the baptism of John” (Acts 1:22) and witnessed Jesus’ ascension. This disqualifies Paul, but Paul claims his vision on the road to Damascus is his witness to the glorified Jesus. The Catechism of the Catholic Church observes this “apparition … established him as an apostle” (No. 659).
No one seems to dispute Paul’s claim to membership among the apostles. In his letter to the Galatians, he mentions “those who were apostles before me” (1:17) and remarks the welcome he received from Peter when he visited him in Jerusalem (see 2:9).