Trolls are God's chosen people. They protect his name from and attack those who promote pagan falsities (i.e. Runescape).
One day while playing Runescape, Jesus got into a pvp match against an uber noob. The noob used hax and Jesus was killed. Being the son of God, he was then resurrected from death in Lumbridge where a nearby church was promoting a blasphemist cult worshipping a false diety called Saradomin (not to be confused with false diety SaraLee).
At once, Jesus sped toward his father and told him about the uber noob who killed him, but God didn't give a fuck until he noticed that all the little noobs were pagan blasphamers. Enraged at the act of the false dieties, he sent forth his own race of mighty warriors known as Trolls to combat the pagans.
Efforts by Trolls to restore the rightful name of Gud or whatever his name is are thwarted by the ultra-right wing propaganda spread by the blasphemers. Their actions are often mislabeled as vandalism and are often subject to censorship.