Classic research has suggested that the more people doubt their own beliefs the more, paradoxically, they are inclined to proselytize in favor of them

Classic research has suggested that the more people doubt their own beliefs the more, paradoxically, they are inclined to proselytize in favor of them. David Gal and Derek Rucker published a study in Psychological Science in which they presented some research subjects with evidence that undermined their core convictions. The subjects who were forced to confront the counterevidence went on to more forcefully advocate their original beliefs, thus confirming the earlier findings.