Jesus had many disciples, that is, learners or students. He chose 12 disciples as an inner core of assistants to help him in his ministry and to receive special instruction. He also appointed them as apostles to carry the gospel message to the world (Luke 6:13). [“Apostle” means “one who is sent,” implying one sent with some authority.] The Gospels relate how Jesus sent the 12 on an evangelistic journey, giving them the authority to preach in his name, heal the sick, and cast out demons (Matt. 10:6-42).
Jesus also showed that evangelism was not confined to the 12 when he also sent out 70 disciples on the same kind of mission with the same authority and capability (Luke 10:1-20). Jesus’ plan for continuation of his work after his departure included the commissioning of 11 of the 12 to be the leaders of the Christian movement, originally called “the way”(Acts 9:2;Acts 19:9).Followers of Christ did not become known as “Christians” until several years later, being so called for the first time in Antioch, Syria (Acts 11:26).
On the night before he died, at the Last Supper, Jesus told the 11 (Judas Iscariot having defected) that he had chosen them and ordained them. When he was with them after his resurrection, he said, “Peace be unto you. As my Father hath sent me, even so send I you. Whosoever sins ye remit, they are remitted unto them; and whosoever sins you retain, they are retained.” He also said, “Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: Teaching them to observe all things whatsoever I have commanded you; and lo, I am with you alway, even unto the end of the World. Amen.”
When the 120 gathered in the upper room after Jesus’ ascension, the first order of business was the selection of an apostle to fill the office left vacant by Judas Iscariot. Matthias was appointed as the twelfth apostle (Acts 1:15-26). Some time later, Saul of Tarsus (Paul) was converted and commissioned by the risen Christ to be “a chosen vessel” to bear Christ’s name “before the Gentiles, the kings, and the children of Israel”(Acts 9:15). Paul became known as the thirteenth apostle. As stated in Mark 16:20,”And they went forth and preached everywhere, the Lord working with them and confirming the word with signs following.”