In "The Devil and Tom Walker" by Washington Irving, the central struggle has to do with Tom's greed.  In the beginning of the story, Tom and his wife both display miserly habits and go so far as to cheat each other.  When Tom is given the proposition of wealth by the Devil, his wife cannot wait for him to accept the offer and attempts to claim it for herself.  Tom finds it a bit amusing when she meets her death during a battle with "Old Scratch," yet he does not learn from her example.  He feels that he is on good terms with the Devil, and his own greed compels him to pursue the deal with the Devil.  His greed takes over him, and after he begins making much money cheating poor landowners and workers, he does not want to share any portion of this with the Devil.  But a deal is a deal, and the Devil comes to claim his share.  When Tom resists, the Devil carries him away on horseback, and his home sparks into flame and is reduced to ashes. 

Throughout the tale, the Devil challenges Tom to see how far his greed will carry him by making conditions to their deal:  Tom will not submit to being a slave trader, yet ironically he believes that robbing hard-working people through exorbitant interest rates on their loans is morally acceptable.  This inner conflict is challenged by the Devil's character, and when Tom does not see the error of his ways, he is punished.