This website as defined by Noah Webster:
Main Entry: res·ur·rec·tion·ist (function: noun)
1 : body snatcher 2 : ONE WHO RESURRECTS
The theme of resurrection is alive and kicking in A Tale of Two Cities, and there is even a resident "Resurrection Man"- one who steals bodies. But though Sydney has sunk low in his own time, I don't think he's ever collected cadavers. So we'll be sticking with the second definition.
In addition to recalling Darnay to life by saving him at his trial, Sydney "resurrects" the other hero again at the end of the novel. In doing this he not only gives Darnay his life back, but he ensures a continuing life for himself. Because of his supreme sacrifice, new life will be breathed into his name, and his story will live on in the hearts and minds of the people. (How sappy. Eugh.)
This site used to be called Hero, but I dropped that because it was too generic. Darnay's also a hero. That epithet could be applied to hundreds of characters. Resurrectionist is much more specific to Sydney, and I think it's a really cool word, even if I can't spell it half the time.