Here, we talk about some folks you and I have known, and (very importantly) how to keep from joining them. I'm talking about the spiritually dead. They may physically continue to exist and have their funerals in their 80's or 90's, but they actually died much younger, perhaps in their teens and twenties. Some are obvious, because they are so busy being who they think that they are supposed to be that they forget who they might actually be.
Others die more quietly, just sort of giving up on their spiritual life.
In either case, they may have been the victims of spiritual suicide. Some commit spiritual suicide voluntarily, such as the people who are so intent on being who others want them to be that they forget to learn who they really are. And then there are the victims of subtlety, whose spiritual suicide is more of a slow and gentle process to the point that it's hard to tell when they actually died. Worse, so many of them do not know that they are dying - or dead.
And of course, there is something positive that might be gleaned from this also. If you know how some people die, it might show you some ways to be more alive.