What metaphors are used in In the Garden of the North American Martyrs by Tobias Wolff?

There is a literal and a metaphorical sense of moral corruption. The inclusion of the word martyr in the title invites readers to consider the themes of moral corruption and sin. Martyrs are those who are willing to die for their beliefs, usually at the hands of unbelievers or sinners. Because their deaths live on in legend and story, the martyrs serve as examples to others of the ultimate triumph of their purity over corruption, good over evil.