Goodman Brown appears to lose his faith after the eerie cloud has passed overhead and he sees pink ribbons falling from the sky. He exclaims at that point, "'My Faith is gone!' cried he, after one stupefied moment. 'There is no good on earth; and sin is but a name. Come, devil; for to thee is this world given.'" Then he tears through the forest becoming a part of the evil scene. When he reaches the devil's meeting, however, he has one last gleam of hope, and appeals to Faith (the symbol representing his own faith) to resist the devil. The mysterious scene ends and Goodman Brown does not know what happened to Faith, but his own lack of faith is evidenced by his despairing behavior for the rest of his life.
He looses his faith when he realizes that his Faith (his new wife) is going to the Dark meeting as well. THat's when he realizes that maybe what he thought is good is now gone.