Many people believed Jesus was many things. Jesus and his 12 disciples tavelled to Jerusalem to celebrate the Jewish holy days of Passover.
After the meal, he was betrayed by one of his closest follower. He was arrested and crucified.
Jesus was resurrected and appeared to a few of his disciples 3 days after he died.
The apostles spreaded the message of Jesus. Small groups of Jews and non-Jews believed Jesus' message.
The first Christians made churches, prayed, and studied the Hebrew bible and early Christian writings. They also ate meals similiar to the Last Supper for remembrance of Jesus' death and resurrection.
Christianity began when Jesus and his 12 disciples travelled to places to spread his message. Most people believed in him, but some people didn't. When Jesus and his 12 disciples went to Jerusalem to celebrate the Passover, Jesus was betrayed and arrested after the meal by one of his disciples. He was crucified and died. Although, 3 days later he resurrected and appeared to a few of his disciples. After he was resurrected, that's how christianity began.