Both Zadok (sometimes spelled Zadoch) and Cutwolfe are condemned to similarly gruesome deaths involving slow torture. Both men get into their situation either by blaspheming against God or causing another to do so, along with other crimes, including murder and attempted murder.
Among his crimes, Zadok, a Jew, sells Jack as an anatomical specimen, whips Jack's courtesan from head to toe, and blasphemes against the Christian faith, saying:
These be they that worship that crucified God of Nazareth; here’s the fruits of their new-found gospel; sulphur and gunpowder carry them all quick to Gehenna.
Zadok is speared as if on a spit and slowly burned to maximize his suffering as he is executed. He is, among other tortures, subjected to
a small oil fire, such as men blow light bubbles of glass with, and beginning at his feet, they let him lingeringly burn up limb by limb till his heart was consumed, and then he died.
Cutwolfe is punished for having killed Esdras of Granado, an act of vengeance for Esdras killing Cutwolfe's brother. Cutwolfe forces Edras to speak blasphemy against God and Christian salvation right before shooting him in the mouth: Edras has no chance to repent of his words and so is condemned to hell. Cutwolfe justifies his act as a fitting vengeance.
Cutwolfe's execution is slow and very painful but, unlike Zadok's burning, involves breaking his bones very gradually, then cutting him with a hatchet in places and pouring boiling lead in his wounds, then cutting out his tongue. The executioner also has
venomous stinging worms ... thrust into his ears, to keep his head ravingly occupied; with cankers scruzed to pieces he rubbed his mouth and his gums; no limb of his but was lingeringly splintered in shivers.
Jack, the narrator, is so horrified by this execution that he straightens out his own bad behavior, marrying his courtesan, giving money to the poor, and hurrying out of Italy as fast as possible to return to England.
Nashe seems to have wanted us to understand that blasphemy is a crime that calls down horrific punishment, as does murder. He wants these executions to deter us from criminal and anti-Christian acts. Also, Nashe wants his readers to understand that Italy is a terrible place, a "Sodom" that it is best to avoid, where horrible executions follow horrible crimes.