One of the most vivid symbols of Christianity is the crown of thorns, which Jesus wore before his crucifixion:
Matthew 27:29
... and then twisted together a crown of thorns and set it on his head. They put a staff in his right hand and knelt in front of him and mocked him. "Hail, king of the Jews!" they said. (NIV)
In the Bible thorns often represent sin, and therefore, the crown of thorns is fitting—that Jesus would bear the sins of the world. But a crown is also fitting because it represents the suffering King of Christianity—Jesus Christ, the King of Kings and Lord of Lords.