From the top of the scene, any ambiguity concerning Claudius' character disappears. He identifies Hamlet as his enemy and plots to have him dispatched to England. He conspires with Polonius to spy on Hamlet yet again. Then, kneeling in prayer before sleeping, the King confesses the depth and severity of his crime. He likens himself to Cain, the primal or first murderer, and admits that he cannot bring himself to ask for God's mercy. "But oh, what form of prayer / can serve my turn?" Claudius knows that he will never abdicate the throne, nor will he give up Gertrude and all "those effects for which I did murder," such as his power and position. He expects to spend eternity in hell.
Hamlet enters as the King kneels with his back toward Hamlet. Hamlet reaches for his sword, and the ambiguity shifts to Hamlet. His Christian morality informs him that because the King appears to pray, he is probably confessing. By ending his life in mid-confession, Hamlet would allow the King to go straight to heaven by virtue of his cleansed soul. Hamlet would prefer to send the King to hell. He has no problem with the immorality of robbing a man of his salvation. Hamlet is capable of imitating King Claudius' cruelty.
Some critics believe that Hamlet vacillates yet again in yet another self-deception of word play. In fact, this moment represents the pivotal point in the play — the moment of truth. Had Hamlet taken charge and acted rather than retreating into his words, he would have prevented the six deaths that follow. Most importantly, the tragic hero might not have met his inevitable end. Then, of course, the play would have been cut short, and no tragedy would exist. Had Hamlet killed Claudius here, he would have more closely resembled Macbeth who murdered innocence — in Macbeth's own words, "Macbeth hath murdered sleep" — by taking the life of an unprotected, unaware King. The action would label Hamlet a villain, not a hero. Claudius survives in order to preserve Hamlet's character.
