Portrait of an Honest Ghost
I have been told on several occasions that the Ghost of Hamlet's Father is not who he claims to be but is a deceptive demon from hell. On one occasion, during a class on Shakespeare, one of my students questioned my reading of the play on the assumption, learned from another class, that the Ghost was demonic and that he was a liar. This misunderstanding of the Ghost's pivotal and crucial role in the play sucks the profoundly Christian lifeblood from Hamlet. If the Ghost is from hell, Hamlet is an idiot and the play's conclusion an ultimately meaningless mess.
I deal with the Ghost's role at considerable length in my book, Through Shakespeare's Eyes. Here, however, is a brief summary of the evidence for the Ghost's honesty:
1. The Ghost is real, and not a figment of the imagination, because Shakespeare goes to considerable lengths to show that it is seen by several people at once (and on more than one occasion) at the play's outset.
2. The Ghost insists, with Hamlet, that the witnesses to the apparition swear upon the sword and not simply by faith, a clear reference to the Catholic position on faith and works and a criticism of the Protestant doctrine of sola fide. Samuel Johnson, amongst others, has pointed out that the sword symbolizes the cross in this scene. Christian knights and soldiers swore upon their swords, which were cruciform and often had a cross emblazoned on the hilt. The insistence that they swear upon the cross turns the play into a crusade for justice. Needless to say, it is somewhat unlikely that a demon would insist that people swear upon the cross.
3. Hamlet, with his customary deliberation (which is not synonymous with the false charge of procrastination that is often levelled against him), goes to great pains to ensure that the Ghost is indeed "honest" and not a lying demon from Hell. He is aware that he will be killing an innocent man if the Ghost is lying about Claudius. He devises the play within the play (a powerful metaphor for the role of art as a conveyer of truth) to test the innocence of the Ghost and the guilt of Claudius.
4. The Ghost does not demand vengeance but justice. Claudius is not only a murderer but a regicide and a fratricide. Furthermore, his crime would have gone unpunished without the timely intervention of the Ghost. Hamlet has no recourse to justice through conventional means because the King is the highest authority in the land. Do those who claim that the Ghost is demonic think that justice would have been served if Claudius had reigned happily, his heinous crime undiscovered and unpunished?
5. The Ghost shows remarkable mercy and forgiveness towards his wife, considering that she has married his murderer. Although Gertrude's direct role in the murder is not clear, it is at least heavily implicit that she was being unfaithful to her husband prior to the murder. The Ghost's charitable disposition towards his unfaithful wife contrasts starkly with Hamlet's venting of his spleen against his unfaithful mother.
6. The symbolism of the play's climax in which poison is synonymous with sin and the sword is synonymous with the cross, ties in with the swearing upon the sword/cross at the play's outset.
7. In a metadramatic sense, Shakespeare's Catholicism is seen in the connection between Claudius and Elizabeth, the latter of whom was responsible for killing Mary, Queen of Scots, whom Catholics believed to be the true queen (Elizabeth as the illegitimate child of Henry VIII's adulterous relationship with Ann Boleyn was seen as usurping the throne).
8. Continuing with the metadramatic background, St. Pius V had excommunicated Elizabeth I, declaring in a papal bull that "Elizabeth, the pretended queen of England and the servant of crime" was a heretic whom no Catholic should serve.
9. At the end of the play, Horatio praises Hamlet as a noble spirit and prays for him in the words of the Latin requiem Mass. Hamlet is the play's hero, carrying out the will of God, which had been revealed to him by the heaven-sent Ghost.
To conclude, there is no way that any Catholic in Elizabethan England would have seen the Ghost as demanding anything but justice, a justice sanctioned by heaven itself in the sense that he had been sent from purgatory (heaven's ante-chamber) to expose the crime of which he had been the victim.