Hawthorne's point is that good people are still good people even they are tempted by evil things. It is our human nature that has this mix in each of us. No one is wholly perfect. The Devil says in his "sermon" to the crowd that "evil is the nature of mankind," but it isn't that black and white. If that was Hawthorne's point, then why is Goodman Brown, the one who REJECTED the offer of the devil, the only who is bitter and cynical in the end of the story? Brown is so disillusioned by the negative in people that he can no longer see any good in them.