A university intellectual, Hamlet finds himself immersed in a world motivated by revenge, lust, envy, and cupidity--carnal desires against which the cerebral prince is ill-equipped. Thus, Hamlet is dubious about battling against them, and his greatest fear is that of taking wrongful action and, as a result, then being humiliated.
- Hamlet worries that the ghost may have not been real and that his killing of Claudius be unjustified; for, after all regicide is a serious matter. If found guilty of this charge, Hamlet will be terribly humiliated.
- When he does decide to kill Claudius, Hamlet sees him praying; again he fears wrongful action, worrying that he may inadvertently make Claudius a martyr and, thus, humiliate himself as a "rogue and villain,"
A villain kills my father; and for that,
I, his sole son, do this same villain send
O, this is hire and salary, not revenge! (3.3.78-81)
The renowned critic Harold Bloom writes,
Hamlet...cannot strike us as a likely avenger because his intellectual freedom, his capaciousness of spirit, seems so at odds with his Ghost-imposed mission.
Further, Bloom contends, Hamlet feels it is humiliating that he should be asked to set a world right, "How all occasions do inform against me." Fearing this humiliation, Hamlet deliberates, procrastinates, and philosophizes all the while remaining in a perpetual state of melancholy because his knowledge of the futility of life deters action--"To be, or not to be...."
Building on mwestwood's excellent response, I think the theme of judgment runs throughout the play. I think if Hamlet assassinates Claudius wrongly--or if his motives aren't pure when he does it--he's worried about damning his soul. We know from his comments about suicide that he's worried about going to hell, and we know from the ghost of his father that his father--whom he compares to "Hyperion," the sun god--is in Purgatory for undisclosed sins.
Hamlet is, as mwestwood notes, a university intellectual but because he attends Wittenberg University, we also know he is a devout Christian, too.
Hamlet lives in a world of duplicity and corruption, but in which (he seems to believe) God may still judge him for his actions. I agree with other comments on e-notes that Hamlet's chief dilemma seems to be between reconciling his own nonviolent nature with the welfare of the kingdom. The concerns about judgment, however, further complicate his decision-making.
I want to make it clear that I myself am NOT a practicing or devout Christian, so I'm not using Hamlet as a soap-box to spout my religious beliefs. But I have to insist that Christian concerns about judgment and the after-life seem to influence Hamlet's motives and concerns about "doing the right thing."