In the framework of applying econophysics ideas in religious topics, the finances of the Antoinist religious movement organized in Belgium between 1920 and 2000 are studied. The interest of investigating financial aspects of such a, sometimes called, sect stems in finding characteristics of conditions and mechanisms under which definitely growth AND decay features of communities can be understood. The legally reported yearly income and expenses between 1920 and 2000 are studied. A three wave asymmetric regime is observed over a trend among marked fluctuations at time of crises. The data analysis leads to propose a general mechanistic model taking into account an average GDP growth, an oscillatory monetary inflation and a logistic population drift.