Social identity or in-group identification is motivated by two forces; one is death anxiety, and the other is self-esteem. Death anxiety is an unconscious force that arises from the awareness of our mortality, while self-esteem functions as a mediator between death anxiety and in-group identification. More particularly, social identity allows the individual to achieve symbolic immortality by identifying with a culture that goes on into the future and thus transcends death.
This phenomenon is implicated in our desire to belong and identify with one group and to uphold its views and ideas against other groups, even disparaging the others who do not share the same views. Thus, death anxiety could be the motivating factor behind group polarization (i.e., in-group vs out-group) and out- group derogation.
The current study yields very interesting results about the role of self-esteem in moderating this relationship. Notably, under normal conditions high self-esteem individuals are more tolerant towards out-group’s views than low self-esteem people; however when reminded of their inevitable death, high self-esteem individuals lose their tolerance and become ardent defenders of their group’s ideas while disparaging the others, the low self-esteem individuals on the other hand exhibit more evenhanded judgments. By contrast, awareness of the meaninglessness of existence or existential anxiety does not affect their tendency to disparage other groups.
Reference:
Baldwin, M. W., & Wesley, R. (1996). Effects of existential anxiety and self-esteem on the perception of others. Basic and Applied Social Psychology, 18(1), 75–95. https://doi.org/10.1207/s15324834basp1801_7