Saint Luke, Evangelist, was a physician and a close companion of the apostle Paul during his missionary journeys. He is traditionally recognized as the author of both the Gospel of Luke and the Acts of the Apostles, providing a detailed, orderly account of the life, ministry, death, and resurrection of Jesus, as well as the growth of the early church. His writings emphasize God's universal mercy, compassion for the outcast, and the active role of the Holy Spirit. His feast day is celebrated annually on October 18.