It doesn’t really “teach” anything, certainly not philosophy or theology. It’s a creepy/fun story about an orphaned boy who grows up in a Graveyard taught by ghosts and with a vampire as his mentor. A lot like Mowgli in the Jungle Book (which is where it gets its title).
Please do not avoid Neil Gaiman’s “The Graveyard Book”. You’d be missing out (no dogs die, almost everyone is already dead – it being set in a graveyard).
“Through dangers untold and hardships unnumbered I have fought my way here to the castle beyond the Goblin City to take back the child that you have stolen!”
You’re right. They both come from the Greek “páthos”, meaning experience, emotion, passion, but also suffering, affliction, disease.