Testing the Strictness Thesis and Competing Theories of Congregational Growth

Building off of Dean Kelley’s and Laurence Iannaccone’s earlier work, we develop a path model of the strictness thesis that investigates and compares how congregational strictness, evangelical theology, demographic characteristics, and denominational identity variously contribute to congregational growth and decline. Using the U.S. Congregational Life Survey (2001), we test this model at the congregational level and find significant support for the mechanisms at the core of both Kelley’s and Iannaccone’s versions of the strictness thesis, particularly that even after controlling for the other dynamics mentioned, congregational strictness has both an indirect and a direct positive effect on congregational growth. We also find, however, that evangelical theology, fertility, and denominational identity all play important roles in the prediction of growth, leading us to assert our integrated model as a new and more fully robust understanding of congregational growth and decline.