Becker introduces the concept of the "vital lie," which refers to the ways in which humans deceive themselves to avoid facing the reality of their mortality. This idea is central to understanding how individuals construct their lives around illusions of permanence and significance, often through cultural and religious practices.

One of the book's key ideas is that humans engage in "immortality projects" to give their lives meaning and to transcend death. These projects can take many forms, such as creating art, building institutions, or contributing to scientific advancements. Becker suggests that these endeavors are driven by a deep-seated need to be part of something that will outlast our physical existence.

Becker explores the dual nature of human existence, where we live in both a physical world and a symbolic world of meaning. This duality creates a tension between our biological reality and our desire for symbolic immortality. Understanding this tension is crucial for comprehending the motivations behind human behavior and the development of culture.