Christianity 101 | National Geographic

About 2,000 years ago, in a far-flung province in the Middle East, a man emerged from the desert with a message—one that would radically alter the course of world events and come to define the lives of billions.

Christianity is a monotheistic religion that centers on the teachings of Jesus Christ, believed to be the son of an almighty Universal God. It is through faith in Jesus Christ and his teachings that believers have access to God and the afterlife. The Christian religion began about 2,000 years ago in the province of Judea in the Middle East. It was a sect of the overarching religion at the time, Judaism, and originally had very few followers.

What's known about Christianity's earliest days and the life of Jesus Christ comes from four books called the Gospels. The Gospels hold that Jesus was born in the first decade BC in the region of Judea. His father was named Joseph, and his mother was named Mary. According to tradition, Jesus was immaculately conceived by God.

In some accounts, Jesus had been trained as a carpenter or a builder, but by the age of 30, he took to preaching, saying that forgiveness of past sins was the key to achieving righteousness. However, the Jewish religious leaders and Roman rulers of the region declared Jesus an agitator. They had him arrested and crucified, nailed to a wooden cross, and left to die.

But the story of Jesus doesn't end with his death. According to the Gospels, the body of Jesus was resurrected by God, his father. If Jesus had built the foundations of the Christian faith, it was a Greek-speaking Jew named Paul who made it a religion. According to Paul, God revealed Jesus Christ to him in a vision. Paul then converted to Christianity and made it his mission to see Christ's teachings as an institution by establishing churches across the Roman Empire.

Paul's actions catapulted Christians from an esoteric Jewish sect to a society of worshipers with reach across the known world. Over the next two millennia, Christianity would go through an unprecedented journey. Scriptures such as the Gospels would be gathered and translated to form Christianity's sacred texts, the Bible.

The Christian faith would branch into many denominations and be practiced by followers on all seven continents. The number of Jesus Christ's followers would grow to two billion, making Christianity the world's largest religion. While religious practice, ritual, and tradition have changed according to the spiritual needs and desires of its billions of adherents worldwide, a man from Judea's simple message of peace and forgiveness remains just as powerful now as it did 2,000 years ago.