Saint Paul the Apostle, also referred to as Saul of Tarsus, was a pivotal figure in the formative years of Christianity. He lived between roughly 5 and 64 or 67 AD, and while not one of the original Twelve Apostles, he dedicated his life to spreading the teachings of Christ to the first-century world. Paul was a Roman citizen born in Tarsus, modern-day Turkey, and he had Jewish roots, being from the tribe of Benjamin. Initially, as a Pharisee knowledgeable in Jewish law, he actively pursued and persecuted early followers of Jesus, viewing them as a threat to Jewish doctrines.

The trajectory of his life was radically altered during a journey to Damascus. During this trip, Paul had a profound vision of the risen Jesus, a moment that has come to be known as the "Damascus Road experience." This spiritual encounter marked his conversion from an adversary of Christians to a zealous advocate of Jesus' teachings. Following this transformation, he spent several years in Damascus and Arabia, after which he returned to Jerusalem to meet some of Jesus' original Apostles. Paul then dedicated his efforts to evangelize, often focusing on spreading the gospel to non-Jewish, or Gentile, communities.

Throughout his life, Paul embarked on three significant missionary trips across Asia Minor and Europe, establishing Christian congregations and disseminating the gospel of Jesus. His letters, known as epistles, to these early Christian communities, such as the Corinthians, Galatians, and Romans, are a considerable part of the New Testament and have significantly influenced Christian theology. Around 57 AD, Paul was arrested in Jerusalem due to conflicts between his teachings and traditional Jewish beliefs. He was later sent to Rome for trial, and according to historical accounts, was martyred there in the mid-60s AD. His impact on the development and spread of Christian thought and doctrine has been profound and enduring, establishing him as an essential figure in the annals of Christianity.