Interact with the idol and choose between the Pray of Safe Journey and the Pray of Comradery. Both prayers have an own cooldown of 48 hours which appears as debuff in your status bar and you will drop all items and all your equipment, only items with the "No drop" effect will stay.
Pray of Safe Journey
This prayer can be used to travel from one protectorate to another. You can choose the protectorate you want to travel to.
Pray of Comradery
This prayer can be used to travel to a guild monument by using its guest code. A guest code gets set at the guild monument in the manage/worship menu.
Locations of the Idols
The green marked areas are the Protectorates, the green dots the admin villages where the idols are standing.