Chalcedonism in-game refers to forms of Christianity pre-schism that followed the definition of the nature of Christ decided at the Council of Chalcedon in AD 451. It would spread across Europe, through the Roman Empire, until the schism. After the schism, Chalcedonism would become Catholicism in the West, and Orthodoxy in the East.
See also: The Great Schism
Bonuses
- Stability cost modifier -10%
- Tolerance of the true faith +1
Mechanics
Chalcedonism possesses no unique mechanics.
Chalcedonism is in the christian group, and all other religions in the christian group pre-schism are considered heretics, i.e. Arianism, Nestorianism, and Coptic. Every other religion will be considered heathens.
Events
Chalcedonism will spread to any neighboring province until the year 867, with an exception to Hellenic provinces in which it's until the year 840.
The Great Schism can happen to Chalcedonist nations any time after the mid-800s.
Convert to 
Chalcedonism
Requirements:
- Stability at least 1
- Is at Peace
Effect:
- Religion Changed to Chalcedonism
- Lose 4 Stability
- [Country] gets Recent Conversion for 5 years giving the following effects:
- +2.00 National unrest
- +20.0% Stability Cost Modifier
Possible for: