Here's why:
* Proper nouns refer to specific people, places, or things. They are capitalized. Examples include:
* People: John, Mary, Queen Elizabeth
* Places: London, France, Mount Everest
* Things: The Mona Lisa, The Great Wall of China
* Common nouns refer to general categories of people, places, or things. They are not capitalized. Examples include:
* People: man, woman, child
* Places: city, country, mountain
* Things: painting, wall, building
"Devil" is a common noun that refers to the general concept of a malevolent supernatural being, often associated with evil. It is not a specific name like "Lucifer" or "Beelzebub," which are proper nouns.