Christians hold in high esteem those who were personally called by Jesus and who walked with Him during His ministry on Earth. That is especially true of the twelve Apostles. The Greek words used for apostle convey both the notions of sending or dispatching (apostolos) as well as the idea of commissioning someone with divine authorization (apostello).
The idea of apostleship might be traced back to the Hebrew notion of an envoy. This Jewish institution would have been familiar to Jesus and is well documented in the rabbinic writings where it refers to “one who has been authorized to carry out certain functions on behalf of another.” A well-known Jewish adage is “a man’s envoy is as himself.”
Among the Twelve disciples, Jesus poured His life into an inner circle that had a key role in establishing the church. Peter, Andrew, James and John were privileged to be with Jesus when He healed Jairus’ daughter (Mark 5:37), and at the Transfiguration of Christ (Mark 9:2). They were the audience at the Olivet Discourse (Mark 13:3) and were with Jesus during His time of agony in the Garden of Gethsemane (Matthew 26:37).
These four men left quite a legacy. Peter is credited with providing the material for the book of Mark and the two epistles given his name. He was the leader of the church in Jerusalem during the first 15 years covered in the first twelve books of Acts, after which James, the brother of Jesus, took over. Peter then became a missionary to the Jews and to a lesser degree, the Gentiles.