1: Not a clinical death, or a permanent one. Spiritual death is figuritive. It describes the ultimate disintegration or corruption of previously sincerely embraced religious beliefs. Probably origially coined in the late 1970s or early 1980s by the Jehova's witnesses' organiztion.
2: Spiritual transgression or treason.
Sister Garland masturbated to music and was not remorseful, she has suffered a spiritual death because she did not beat herself with insane grief as is our tradition. She will not be accepted when the end comes.