Once Religious, Always Religious?

A friend of mine once said, "Once a Catholic, always a Catholic." And he's no longer a practicing Catholic. The idea behind his saying was that religion sticks with you, even when you no longer consider yourself religious. Is this true? And if so, what makes religion so hard to shake?

A new line of research has uncovered what is known as "religious residue:" the tendency for religious psychology and behavior to persist even after people leave religion. This work, which has sampled participants from four different countries (Van Tongeren et al., in press) and has examined both adults and adolescents (Van Tongeren et al., 2020), has revealed a few key findings.