Eventually, when Christianity became the state church of the Roman Empire, Samaritans were barred from worshiping on Mount Gerizim. In 475 CE a Christian church was built on its summit. In 529, Justinian I made Samaritanism illegal, and arranged for a protective wall to be constructed around the church. As a result, the same year, Julianus ben Sabar led a pro-Samaritan revolt, and by 530 had captured most of Samaria, destroying churches and killing the priests and officials. However, in 531, after Justinian enlisted the help of Ghassanids, the revolt was completely quashed, and surviving Samaritans were mostly enslaved or exiled. In 533 Justinian had a castle constructed on Mount Gerizim to protect the church from raids by the few disgruntled Samaritans left in the area.