When Young Goodman Brown dreams that he hears Faith's voice in the sky above him and then sees that "something fluttered down through the air," which turns out to be a pink ribbon, his Puritan belief system collapses in a desperate cry:
'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.'
After having his world view turned upside down by seeing everyone he believes is good on the way to Satan's convocation of sinners, Goodman Brown is presented with the final proof that his faith has been misplaced. When he cries that his faith is gone, he means that not only is his wife, Faith, gone to join Satan, but also that his own faith is finally and completely gone.
When Goodman Brown begins his journey, he believes that, no matter what he does, he can rely on his wife, Faith, to lead him to heaven:
'Well, she's a blessed angel on earth; and after this one night I'll cling to her skirts and follow her to heaven.'
After his dream in the forest, however, when he hears Faith overhead apparently on her way to Satan's meeting and then sees the irrefutable proof--Faith's pink ribbon--that she is indeed on the same journey he is, this incident is the strongest proof for Goodman Brown that everyone, no matter how outwardly "faithful," has been corrupted by Satan.
Young Goodman Brown's loss of Faith, his wife, the only person in his life for whom he has any trust, crushes the last bit of conventional religious faith in him--he loses his wife and his faith at the same time.