Existing research in social psychology has not examined how significant changes in a person's moral values, political beliefs, or preferences affect perceptions of that person's authenticity. This dissertation addresses this gap by examining how such changes impact the perceived authenticity of the individual. Through a bottom-up analysis of lay definitions of authenticity, four key features of authentic beliefs are identified: adherence to core values, honest expression of beliefs, consistently acting in accordance with one's beliefs, and belief resilience despite pressure to change. This led to the development of a reliable scale of belief authenticity. The data show that minimal information about a person's belief change typically results in perceptions of reduced authenticity, regardless of agreement. Additionally, understanding the reasons behind belief changes and framing them as aligned with core moral values can mitigate the negative impact on perceived authenticity.