As Antonio dreams about Tenorio killing Narciso, the author uses a biblical allusion to Romans 12:19 to demonstrate his struggle with the morality of revenge. In his dream, as Antonio begs God not to listen to the Virgin of Guadalupe when she says she’ll forgive Narciso for his murder, God shouts:
[You] would also have her taint her hands with the blood of vengeance - Vengeance is mine!
In this passage Anaya is referring to the Bible verse Romans 12:19, in which God says: “Do not avenge yourselves, beloved, but leave room for the wrath of God, for it is written, 'Vengeance is mine, I will repay, says the Lord.'” The appearance of this allusion in Antonio’s dream points to the Catholic idea that vengeance belongs to God alone and should not be pursued by humans. Antonio is, in general, suspicious of what he sees as the unbending severity of the Christian God, but here he’s adamant that God should punish Tenorio. In the dream, God chastises him for his hypocrisy, saying that he can’t take the more forgiving path the Virgin offers and still expect Tenorio to be severely punished. The dream forces Antonio to confront the tension between his feelings of anger with Narciso and his belief that the more forgiving ways of the Virgin of Guadalupe are a better moral choice than vengeance. It's an important moment in Antonio's development when he recognizes that morality is not always black and white; there can be nuances to what is morally good or bad depending on the situation.