In Hawthorne's Young Goodman Brown, the primary obstacle that leads to major complications in the plot come from Brown himself.
Brown is a man who believes himself to be upright and blameless in his Christian walk; but with intent, he enters the woods one evening, even though Puritans believed that the woods harbored the Devil, with "evil purpose." After this one night, Brown promises, he will return home and never leave again.
As Brown moves along he meets up with an old man—who looks a great deal like Brown; he is actually the Devil. As they walk and talk, Brown realizes that his ancestors were in league with the Devil for generations. Brown is surprised! And...
Brown initially considers his decision to go on his unholy errand an exceptional one, but he soon discovers that other presumably exemplary villagers are on the same path...
Faith! Faith!...look up to heaven, and resist the wicked one.
And, maddened with despair, so that he laughed loud and long, did Goodman Brown grasp his staff and set forth again, at such a rate that he seemed to fly along the forest path rather than to walk or run.
Brown overcomes this obstacle by refusing to associate with the decent (but imperfect) people in the town; and he alienates himself from his wife. He becomes a grumpy, lonely old man. He is suspicious of all and is nothing that resembles the fine Christian man he believed he was: for he doesn't spread the Gospel, he does not care for the less fortunate, and he does not practice forgiveness. In essence, the tenets of his faith with which he rejects these people are the same things he forsakes himself.
In a religious context, all are sinners. The townspeople are no different than Brown, but he can only see their sin—not his own. He is particularly harsh even though he can even be certain that what he saw was not simply a dream.
The biggest obstacle is Brown's inability to see that no one is perfect—not even him. He lacks faith in his wife and fellowman, loses his own faith, and becomes an angry, suspicious and lonely old man. He is hypocritical for judging others and not himself.