Judas Iscariot
There are several explanations as to why Judas betrayed Jesus. In the earliest account, in the Gospel of Mark, when he goes to the chief priests to betray Jesus, he is offered money as a reward, but it is not clear that money is his motivation. In the Gospel of Matthew account, on the other hand, he asks what they will pay him for handing Jesus over. In the Gospel of Luke and the Gospel of John, the devil enters into Judas, causing him to offer to betray Jesus. The Gospel of John account has Judas complaining that money has been spent on expensive perfumes to anoint Jesus which could have been spent on the poor, but adds that he was the keeper of the apostles' purse and used to steal from it.
Treason
In William Shakespeare's play "King Lear" (c. 1600), when the King learns that his daughter Regan has publicly dishonoured him, he says "They could not, would not do 't; 'tis worse than murder": a conventional attitude at that time. In Dante Alighieri's "Inferno", the ninth and lowest circle of Hell is reserved for traitors; Judas Iscariot, who betrayed Jesus, suffers the worst torments of all: being constantly gnawed at by one of Lucifer's own three mouths. His treachery is considered so notorious that his name has long been synonymous with "traitor", a fate he shares with Benedict Arnold, Vidkun Quisling, Marcus Junius Brutus (who too is depicted in Dante's "Inferno", suffering the same fate as Judas along with Cassius Longinus). Indeed, the etymology of the word "traitor" originates with Judas' handing over of Jesus to the chief priests, captains of the temple and elders (Luke 22:52): the word is derived from the Latin "traditor" which means "one who delivers."
Christian theology and political thinking until after the Enlightenment considered treason and blasphemy as synonymous, as it challenged both the state and the will of God. Kings were considered chosen by God, and to betray one's country was to do the work of Satan.