The New Testament includes 27 book: four Gospels (Old English, “good news”), the Acts of the Apostles, 21 letters (called Epistles), and the Book of Revelation. These books were written in Greek over a period of about a century, from ca. A.D. 50 (the earliest of Paul's letters) to the mid-second century A.D. The arrangement of the books is chronological according to events, rather than composition: the Jesus (Gospels), the beginning of the Church (Acts), advice to churches and the beginnings of Christian theology (Letters), and the end of the world and final salvation of believers (Revelation). Little is known about the actual authors of the books, apart from some letters genuinely attributable to Paul.
There are four Gospels, each attributed to one of Jesus' disciples: Mark, Matthew, Luke, and John. The central story in all of the Gospels is the suffering and death of Jesus, who was executed by Roman soldiers for claiming to be the Son of God, and thereby gravely threatening the authority of Jewish scholars called Pharisees. The earliest Gospel is that of Mark, written around A.D. 70, the time of the fall of Jerusalem and the destruction of the Second Temple by the Romans. Luke and Matthew were written during the late first century, using the Gospel of Mark, already well known, as a source. Matthew, Mark, and Luke are called the Synoptic ("seen together") Gospels because they tell essentially the same story of Jesus' life, ministry, Crucifixion, and Resurrection in complementary fashion.
The author of Mark gathers the sayings of Jesus and stories of his life and ministry from the oral traditions of the early church. Beginning with John's baptism of Jesus, he goes on to tell of the miracles Jesus performed, such as calming the waters and feeding the multitudes with loaves and fishes, and then proceeds to detail the circumstances surrounding Jesus' journey to Jerusalem, death, and Resurrection. According to Mark, only after the Crucifixion are Jesus and his mission fully understood by the people, and he is recognized as the son of God.
Unlike Mark, Matthew states at the outset that Jesus is the Messiah. He describes the story of his birth in Bethlehem, the adoration of the Magi, the wrath of Herod, and the flight of Mary, Joseph, and Jesus to Egypt. The narrative of Jesus' ministry includes the Sermon on the Mount and the recognition of Jesus as the Messiah by his disciples. The author of Matthew contrasts the Old Testament time of prophecy with the era of God's fulfillment in Jesus: the believer needs to receive Jesus to be part of God's eternal kingdom.
Luke begins with the birth of John the Baptist and then relates the story of Jesus' birth. He goes on to describe the conflicts with the Pharisees, the journey to Jerusalem, Jesus' death, Resurrection and appearances to his disciples, and his Ascension to Heaven. Luke emphasizes Jesus' concern with the poor and the duties of the rich to the poor. The stories of the Good Samaritan and the Prodigal Son are found only in the Gospel of Luke.
The Gospel of John was written later than the Synoptic Gospels, around A.D. 90-120, but was composed without their reference. Its approach to the story of Jesus is distinctively different. It begins with the assertion that the eternal Word is embodied in Jesus, but the focus is not on the everyday moral and religious implications of Jesus' teaching, but rather on his claims to be the Messiah. John omits the parables, the Sermon on the Mount, and other narrative elements that characterize the three earlier Gospels, and instead focuses on the conflict between Jesus and the Pharisees, and more broadly, Jesus versus the Jews. The Gospel ends with Jesus' death, Resurrection and appearances to the disciples. (The New York Times ‘Smarter by Sunday – 52 Weekends of Essential Knowledge for the Curious Mind’)