What do you think Hawthorne's purpose was for writing this story?

It can be hard to tell what an author's intention was in writing a particular text, but Hawthorne often returns to the same subjects again and again: religion, sin, and guilt.  "Young Goodman Brown" doesn't seem to be an exception.  Goodman Brown treats religious faith, symbolized by Faith, his wife, rather casually.  Though Faith "sadly" asks him not to go into the forest that night, he insists that he must, and though she seems "melancholy"...

It can be hard to tell what an author's intention was in writing a particular text, but Hawthorne often returns to the same subjects again and again: religion, sin, and guilt.  "Young Goodman Brown" doesn't seem to be an exception.  Goodman Brown treats religious faith, symbolized by Faith, his wife, rather casually.  Though Faith "sadly" asks him not to go into the forest that night, he insists that he must, and though she seems "melancholy" when he looks back at her, he continues on his path.  He thinks to himself, "'after this one night, I'll cling to her skirts and follow her to Heaven.'"  However, this is not how faith is supposed to work: one cannot simply lay it down and pick it up whenever it is convenient.  Brown takes his faith, and Faith, for granted, assuming that they will be waiting for him, unchanged, whenever he is ready to return to them.  In short, they aren't.  Whether he actually sees Faith in the woods at the witches' Sabbath, or whether it was just a dream, his relationship with God and the world has been changed forever by his own faithless behavior.  Therefore, I believe that Hawthorne may have intended this text to be a sort of meditation on faith, as it conveys the theme that real faith is something a believer always carries with them.