it's either suicide (the feeling of loneliness and despair, the anger towards god [the creator] "would you tell him what to do")
or it's murder
my opinion, not fact.
A possible meaning (Off of the Funeral Portrait website)?
To Rid The Disease: A person's friend, parent, relative, lover(You pick which one) is on thier death bed. The person who is still alive is wondering whether that person deserves to live, or to die. Like ridding the world of a disease, which happens to be a person.