Minor Gods like Lloth or Sharess have a distinct physical existence and location, so you can actually track them down, meet them, and (in theory) kill them. But even then it's really unlikely and gods tend to not really die.
Major Gods like Shar, Bane, Mystra, Kelemvor, Tiamat, or Tyr don't exist in any particular place. When you meet them face to face, that's an avatar and defeating an avatar isn't typically going to have any significant impact on a major god.
