I saw that this game has religions, but i don´t know how does it work.

Lukasz said in steam that he works on something who know maybe its religions or nuclear bomb? 
 
 

Hi I have such an idea to use religion in AOC Game > Editor > Create religion > Religion symbol creator Game > Scenario editor > Random scenario > Continents > Wasteland> Civilizations > Provincies > Religions(they work much like cores) In the game Another religion in its own province promotes instabilit  
 
Sorry for my English I use google translator
   
G
 

Can it be done by fans, or is it impossible without open source?

We all know there is a religion folder already but there are no religion in game. 
Before Lukasz add religion, we should suggest him how religion should work and improve religion ( if he currently making ).
 
Mechanism 
- Religion map mode. 
- Religion statistics. 
- Religion work almost the same as population. 
- It has percentage in province and diplomacy menu.
- Province have low stability if your religion is minority or have many other religion. 
- Convert province work just like assimilation. 
- Defender of faith. ( only work before 1900 )
Have a window just like HRE - Defender of faith on top and a list of nation with same religion (each religion has it's own).  Have statistics - a list of religion and the country that have the title on the right side.  Nation with high population and economy can claim the tile.  If a nation defeat in a war against other nations with different religion, the tile gone.  Title can be taken from others if the other nation is stronger.  Nation that have the title will get +20 relations to other nations with same religion and +1 diplomatic point every turn.  Can call for crusade/jihad - war on other religion that have -50 relation, can call other nations with same religion into war.  Christian nation need pope permission ( if papal state exist ) to call crusade. Pope can call for crusade with nation that have -50 relations even without the title. Defender of faith change name to caliph only to muslim religion. - Relations 
Nation that have different religion than you will have -10 relations.  Same religion will have +10 relations.  When you conquer to much nation with same religion, other nations that have same religion will get -50 relation and defender of faith can call for jihad/crusade.  - Vassals 
You can force vassals to convert but you will get -30 relations from your vassals. Vassals gain 50% liberty desire. Other nations that have same religion as vassal is more likely to support their independence.  - Tolerance 
-10 to +10 Higher tolerance means higher stability if a province is have more than one religion.  Tolerance can be increased in technology - unlock at 1800. Higher tolerance increase relations from other nation, negative tolerance decrease relations.  Different government type have different tolerance.  - Atheist 
-5 tolerance from all religion.  Few population change to atheism in 2000 ( mostly Christian)