Apostle

In Matthew, Mark and Luke, Jesus appoints 12 disciples as apostles. They are a distinct group of disciples and representatives of Jesus.

The word apostle (in Greek: apostolos) means “the one who is sent”: a messenger or representative. Outside of the Bible there is no specific profession with the title apostle. The background to the use of apostolos in the New Testament lies in the Old Testament, where some people were called messengers from God, such as Moses and the prophets.

The three Synoptic Gospels each name the 12 apostles, sometimes with further identifying features. Those features might differ per Gospel. For instance, it may be said that Simon was called Peter, or that Jesus gave him the name Peter. Thaddaeus and Jude, the son of James, may have been two different people, but traditionally the two names are thought to be different names for one person.
 

The apostles become the representatives of Jesus after his death. They go out into the world to spread the news of his resurrection. In the New Testament they are therefore seen as the founders of the Church, which is why believers must take care with the message and the teachings of the apostles.

After Judas’ betrayal, Matthias is appointed as the 12th apostle, according to Acts 1:15-26. In the Gospels and Acts the group of apostles seems clearly defined. However, from Paul’s letters it seems that this was perhaps not initially the case. Paul calls himself an apostle as well (for example in Romans 1:1). He also speaks of others using this term (for example in 2 Corinthians 12:11-13).
In the early Christian text, the Didache (11:3-6), from around AD 100, travelling Christian prophets are still called apostles. It was not until later that the consensus arose that there were only 12 true apostles — and Paul, of course.