I don't think the issue is that they "have a tendency to believe in things" so much as they are among of group of people who've voluntarily associated on the ba

I don't think the issue is that they "have a tendency to believe in things" so much as they are among of group of people who've voluntarily associated on the basis of shared beliefs. Looking through the article identifies other groups like immigrant communities as other popular targets. The hint is in the "affinity" part.