Jesus and his Apostles teachings formed the basis for Christianity and after his death, resurrection, and accension, the Apostles continued this task of speading his life and teachings. One of the Apostles, Peter, became the leader of the group after Jesus died. Peter traveled to a few Roman cities and taught about Jesus in the Jewish communities there. Eventually he went to live in Rome, where he had much authority among Jesus's followers. In later years after the Christian Church was more organized, many people looked back to Peter as its first leader.

Probably the most important figure in the spread of Christianity after Jesus's death was named Paul of Tarsus. He had never met Jesus, but Paul did more to spread Christian ideals than anyone else did. He was so influential that many people consider him an additional Apostle. After he died, Paul was named a saint, a person known and admired for his or her holiness.

Like most of Jesus's early followers, Paul was born Jewish. At first he didn't like Jesus's ideas, which he considered a threat to Judaism. For a time, Paul even worked to prevent the followers of Jesus from spreading their message.

According to the Bible, though, one day while Paul was traveling to Damascus he saw a blinding light and heard the voice of Jesus calling out to him. Soon afterward, Paul became a Christian. After his conversion Paul traveled widely, spreading Christian teachings. As you can see on the map, he visited many of the major cities along the eastern coast of the Mediterranean on his journeys. In addition, he wrote long letters that he sent to communities throughout the Roman world. These letters helped explain and elaborate on Jesus's teachings.

In his letters Paul wrote at length about the Resurrection and about salvation. He also mentioned ideas of the Trinity. The Trinity is a central Christian belief that God is made up of three persons-God the Father, Jesus the Son, and the Holy Spirit. But even though there are three persons, there is still only one God.

The first Christians worked to spread Jesus's teachings only among Jews. Both Jews and non-Jews were attracted to Christianity by Paul's teachings. In time, this helped the Christian Church break away from its Jewish roots. But some early Christians, including Paul, wanted to introduce Christianity to non-Jews as well. As a result, Christianity began to spread in the Roman Empire. Within a hundred years after Jesus's death, historians esti- mate that thousands of Christians lived in the Roman Empire.

Christianity spread quickly in many Roman communities. But as it grew more popular, Christianity began to concern some Roman leaders. They looked for ways to put an end to this new religion.

From time to time, Christians trying to spread their beliefs faced challenges from local officials. Some of these officials even arrested and killed Christians who refused to worship Rome's gods. We call such people who suffer death for their religious beliefs martyrs (MAHR-tuhrz). Many leaders of the early Christians-including Peter and Paul-were killed for spreading Christian teachings. Even today, Christians honor them as martyrs and saints.

Most of Rome's emperors let Christians worship as they pleased. A few emperors in the 2OOs and 300s, though, feared that the Christians could cause unrest in the empire. To prevent such unrest, these emperors banned Christianity. This led to several periods of persecution (puhr-si-KYOO-shuhn) against Christians. Persecution means punishing a group because of its beliefs or differences. Because their religion had been banned, Christians were often forced to meet in secret. To arrange their meetings, they used secret symbols to identify people who shared their beliefs. One of the most common sym- bols they used was a fish. The fish became a Christian symbol because the Greek word for fish begins with the same letters as the Greek words for Jesus and Christ.

However, despite the persecution, Christianity continues to spread throughout the Roman Empire. Eventually, even the emperor of Rome himself became a Christian.

The emperor who became a Christian was Constantine (KAHN-stuhn-teen). He came to power in 306 after fighting and defeating many rivals. According to legend, Constantine was preparing for battle against one of these rivals when he saw a cross in the sky. He thought that this vision meant he would win the battle if he converted to Christianity. Constantine did convert, and he won the battle. As a result of his victory he became the emperor of Rome.

As emperor, Constantine removed bans against the practice of Christianity. He also called together a council of Christian leaders from around the empire to clarify Christian teaching.

Almost 60 years after Constantine died, another emperor, Theodosius I (thee-uh-DOH-shuhs), banned all non-Christian religious practices in the Empire. Like Constantine, Theodosius was a Christian. As emperor, he called together Christian leaders to clarify church teachings. He wanted to be sure that all Christians believed the same things.