The "strict-church thesis" says that strict religions thrive while lenient religions decline. This has been a favorite among evangelicals since first articulated in Dean Kelly's 1972 Why Conservative Churches Are Growing.
Perhaps the best defense of the thesis has been Santa Clara University's Laurence R. Iannaccone's influential 1994 essay, "Why Strict Churches Are Strong."
Iannaccone argued that "strict churches proclaim an exclusive truth — a closed, comprehensive and eternal doctrine. They demand adherence to a distinctive faith, morality, and lifestyle. They condemn deviants, shun dissenters, and repudiate the outside world." He concluded that doctrinal and behavioral strictness "increases commitment, raises levels of participation, and enables a group to offer more benefits to current and potential members." Consequently, he says these groups "enjoy a competitive advantage over their opposites."
We evangelicals have long chalked up our success to this thesis. People are leaving ...1