The New Testament was written by multiple authors, primarily Jewish Christians who lived in the Roman Empire. The collection includes 27 books traditionally attributed to nine main authors. The Apostle Paul is credited with writing thirteen letters (epistles), though some are disputed. These letters include Romans, Corinthians (1st and 2nd), Galatians, Ephesians, Philippians, Colossians, Thessalonians (1st and 2nd), Timothy (1st and 2nd), Titus, and Philemon. The four Gospels—Matthew, Mark, Luke, and John—are attributed to their namesakes: Matthew and John were apostles and eyewitnesses to Jesus; Mark was a companion of Peter; and Luke was a companion of Paul. Other New Testament books like Acts, Hebrews, James, Peter's letters (1st and 2nd Peter), John's letters (1st, 2nd, and 3rd John), Jude, and Revelation were written by various authors, some known and some uncertain. Overall, the New Testament was written by men in the first century who were either apostles, close companions of apostles, or early Christian leaders, authoring texts to preserve the teachings and legacy of Jesus Christ and guide the early church.