Django was a good example, Samuel L Jackson's character was a lost cause but most of the other slaves were not.
12 years a slaves is another good example, the Africans that left him hanging (dying) while they went on working are savable. The just may not be convertible until their humanity is returned to them, District 9 is a good example of what i mean. The character in that move knew he wouldn't be able to convert his people so his plan was to leave and return back with a force of concious members of his race to save them and return their humanity by returning them to their natural state of being (I.E. religion).