In "Dark Side of the Moon" by Sherrilyn Kenyon, a powerful notion is conveyed through the quote, "You don't knock on the devil's door, boy, unless you want him to answer." This statement serves as a cautionary warning about the dangers of engaging with malicious forces or tempting fate. It suggests that one should be mindful of the risks involved when confronting dark powers or making dubious choices. The devil symbolizes not just evil but also the consequences that come with seeking out challenges that may lead to harm.

This prominent message emphasizes the importance of awareness and the potential ramifications of one's actions. It encourages readers to think twice before diving into situations that can have dangerous outcomes. Ultimately, Kenyon's work reminds us that some paths should be avoided entirely, as the consequences of inviting trouble into our lives can be severe. The quote encapsulates the theme of battling inner and outer demons, urging caution in the face of temptation and deceit.