Within the sociopolitical infrastructure dominated by various churches during the middle ages evolved a piece of propaganda forming into a deep concept.
People that extend their lives through the occult to became immortal by placing their life force within a phylactery.
-First let me say that this is all propaganda and is
mostly irrelevent in a modern worldalthough it does show
universal and historical philosophies.
Traditionally this is a sense of evil. You extend your life because you are deny yourself the passage into heaven and the afterlife.
-In a fundamentalist world you can easily understand
why people would be against this.
Now as the propaganda slowly began to evolve. People questioned how? How did they do it? People grew a bit more logical and started question this during the Renaissance period. How did they do it then? Well the answer played off some of the primary fears: Death being forgotten and torture. They devised a way that a Lich achieves this by murdering people and trapping their souls in hell. They're bodies would be without tomb or record of what happened.