Young Goodman Brown's encounter with the devil or evil had a negative effect on him. Because he saw, whether in a dream or reality, that the people in his community were not wholly good and could be tempted by evil, he became a grim, unpleasant person. The end of the story sums up the ways Goodman Brown's life was soured by his experience:
A stern, a sad, a darkly meditative, a distrustful, if not a desperate man, did he become ... Often, awaking suddenly at midnight, he shrank from the bosom of Faith, and ... when the family knelt down at prayer, he scowled, and muttered to himself, and gazed sternly at his wife, and turned away. And when he ... was borne to his grave ... they carved no hopeful verse upon his tombstone; for his dying hour was gloom.
Hawthorne wants us to learn not to be overly judgmental or expect too much of the people around us. Young Goodman Brown never matured beyond his childlike thinking in which people were either all good or all bad. He expected his pastor, his Sunday School teacher, and wife to be wholly pure. However, nobody is that way in real life. As we mature, we come to understand that all people are mix of good and bad qualities, and we learn to love them despite their flaws. Through his "dream," Goodman Brown perceived flaws in the people around him and could never get over it: Hawthorne wants us to know that is a destructive way to live.