An apostle is someone has been “sent out” (based on the Greek word apóstolos, “to send”). The New Testament applies this term to people who have been commissioned and sent as witnesses of Jesus’s teachings and identity. In traditional usage, it specifically applies to eyewitnesses of the risen Jesus who have been appointed to special offices of authority in the early church; it’s usually restricted to the first generation of Christian leaders. The term is sometimes confused with “disciple” because there is a great deal of overlap in the two terms’ application: the 12 disciples, for instance, were all apostles, and so one occasionally hears them referred to as “the twelve apostles.” There were, however, other apostles, including Paul, who were not members of Jesus’s 12 disciples.

A religious ritual central to Christian worship, baptism is usually practiced as an immersion, sprinkling, or washing with water and is a rite of entry into the Christian faith. It is attested to throughout the New Testament, having already developed as a common ritual before Jesus’s public ministry began. It was used by John the Baptist as a sign of repentance and commitment to God, likely derived from the Jewish tradition of ceremonial washings for purification.