In his Apology, Bunyan affirms his aim to strengthen religious belief through fiction. He attacks the popular misconception that religion and fiction are enemies, asserting that the Bible contains many fictional parables. Bunyan also states that he wrote his work mainly for himself, to further his own spiritual development.

Beginning the allegory, the narrator tells of his wandering through the wilderness, entering a den to sleep. He dreams that he sees a man in rags holding a book and crying. The man, named Christian, is visited by Evangelist, a spiritual guide who tells him he must leave his hometown, the City of Destruction, with a heavy burden on his back. Christian tries to convince his family to come with him, but they think he is mentally unwell and will recover. Instead of attempting to persuade them further, Christian leaves home.

Christian tries to convince his neighbors Obstinate and Pliable to accompany him. Obstinate refuses, but Pliable agrees, though he is soon discouraged when he and Christian fall into a muddy pit called the Slough of Despond. Christian sinks because of the burden on his back. A man named Help pulls him out. Disappointed, Pliable turns back home. Walking alone now, Christian meets Worldly Wiseman, who urges him to throw down his burden. Although Christian distrusts Wordly Wiseman, he nevertheless listens to Wordly Wiseman speak. Later Evangelist returns to reproach Christian for listening to Worldly Wiseman.

Evangelist kisses Christian goodbye and wishes him well, and Christian resumes his journey. He comes upon a Wicket Gate and reads a sign hung above it that says to knock. A serious-looking attendant named Goodwill appears. Goodwill asks where Christian is heading, and Christian tells him he is on his way to Mount Zion, also known as the Celestial City, to be saved from the wrath soon to be unleashed on the City of Destruction.

Goodwill announces that he wills the gate to open. As it opens, he pulls Christian in, explaining that he is saving his guest from Beelzebub’s arrows shot from a nearby castle. With Christian safe inside, Goodwill requests an account of his journey so far. Before agreeing, Christian asks whether he can first set down his burden. Goodwill says no, explaining that it must be carried and will drop off naturally when no longer needed. Christian reports his progress so far. Satisfied, Goodwill then sends Christian to a nearby house where the Interpreter lives, saying that the Interpreter may show Christian many helpful things.

The Interpreter invites Christian into his home. He shows Christian a picture of a serious man in a crown. Christian asks who it is, and the Interpreter tells him that the man saves souls and promises a better world beyond this one. Next Christian enters a large, dusty parlor where the Interpreter orders a man to sweep. Then at the Interpreter’s command, a woman comes in and sprinkles water on the floor, cleaning it further. Christian asks what this means, and the Interpreters explains that the man’s sweeping is the law of the Old Testament, while the woman’s washing is the gospel of the New Testament. Both are necessary parts of faith.