NOTE: information below is outdated and not inline with the current implementation.
The Currency in Sanctorium are called Trade Points (Empyros!?) for the time being.
You can acquire Trade Points in multiple ways. On Incarnation you will be granted a small amount of Trade Points to get you started. Trade Points are used to power the Economy in Sanctuary.
Production buildings (factories of sorts) produce items which are required by other Production/Consumption buildings. For example, the Sawmill requires Wood from the Woodcutter which in turn requires Trees that are planted by the Forester.
Each item Produced has a Minimum price in Trade Points.
As a City grows the need for standard goods grows as well. These standard goods are Produced by certain buildings, the higher the need, the more of these buildings get constructed by the City's authorities, these buildings are neutral and the goods produced are owned by the City.
Some types of Neutral buildings can be bought from the City for Trade Points. Once you acquire a Neutral building, all future produced goods will be owned by your Religion and can thus be sold. It might be a good idea to buy all the Neutral buildings of a certain kind in a city to influence the price and make more Trade Points.
There are multiple Religious buildings which can be constructed. Chapels, Churches and similar buildings can ask for Donations of Trade Points from your Believers. The more Donations you ask from your Believers the bigger the chance they'll lose Faith in you, so be careful on the number of Donations you ask from your Believers.
In some cases a city dries out of certain goods, for example the population shrinks (diseases, migration, etc) and they run out of Production buildings. In these cases, the City's authorities can commence a Trade mission to another City to acquire some of the required Goods.