What is the theme in Pet Sematary by Stephen King?

Love is a theme in the book. The grieving process, or how mankind deals with loss, is the core concept behind Pet Sematary. Stephen King does a nice job of presenting the clinical stages of grief and the emotionally wrenching feelings that accompany those stages. It is easy to understand, intellectually, that denial is a part of the grieving process. It is significantly harder for Louis to accept that he is in denial about Gage's death because he is in the thrall of painful emotions. Pet Sematary is an exploration of every parent's greatest nightmare, the loss of a child.