Goodman Brown’s guilty purpose is forsaking his wife literally, and his religion metaphorically.
It should be noted that this story is somewhat open to interpretation, as with many matters of faith. Here is one interpretation.
In the story, Goodman goes for a walk in the woods. However, he has to leave his wife Faith to do so.
“Poor little Faith!” thought he, for his heart smote him. “What a wretch am I to leave her on such an errand! (p. 4)
He feels bad for leaving her on the one hand, and resents her for keeping him on the other. He is torn. In religion, we call this a crisis of faith. Goodman has to decide whether he will stick with his faith or wander from it. He takes a “dreary” road, and he is aware of the “evil purpose” on which he is journeying (p. 4).
When Goodman is walking, he comes across a traveler in the form of an old man. He realizes this man is the Devil. He is not sure what to do. He notes that his father, and his father before him, have never gone into the woods “on such an errand” (p. 5). He is convinced that they never strayed, and were never tempted by the devil.
We have been a race of honest men and good Christians since the days of the martyrs; and shall I be the first of the name of Brown that ever took this path and keep…(p. 5)
The Brown family has not been the virtuous sort that Goodman thinks though. The Devil explains that they have been known to commit sins, such as massacres against the Indians, in the name of God. Faith and goodness, Brown realizes, are not so black and white as he thought.
In the end, Goodman returns home but does forsake his wife and his faith. He turns into a grumpy old man.
Goodman Brown’s crisis of faith is one that is typical of most young men, but particularly important for the colonials in the strict Puritan society. Whatever the Church says is right is right. Goodman realizes this is not necessarily the case. After his journey into self-reflection, he realizes that everyone is a hypocrite, and it turns him bitter. He loses faith, and Faith, forever.