A three-state dynamical model for religious affiliation

• Presents a generalised class of the ‘three state’ model of social groups.
• A range of these models are examined in relation to data for religious commitment in post WWII Northern Ireland.
• These models suggest that there have been negligible religious conversion/reconversion rates with in Northern Ireland over the last 70 years.

In the last century the western world has seen a rapid increase in the number of people describing themselves as affiliated with no religious group. We construct a set of models using coupled differential equations in which members of a society can be in one of three groups; religiously committed, religiously affiliated or religiously not affiliated. These models are then used to analyse post World War II census data for Northern Ireland.