Claudius is at prayer, and Hamlet surely doesn't want to send Claudius to heaven after he is absolved by prayer. Hamlet decides to wait until Claudius is involved in one of his usual, sinful and impure acts. He comes to the conclusion that he must send Claudius to hell in order to fulfill his father's wishes completely. This excuse for delay indicates that he is not ready to commit the deed yet.
In Hamlet's final soliloquy, he asks himself why he has waited so long to restore the honour to Denmark. Fortinbras and his army prove that men will dies solely for honour. Hamlet is now positive, without any hesitation, that he must do the same, even if it means his own life will be taken in the process. He will not wait any longer, and will fulfill his responsibility as a loyal son and Prince of Denmark.
Hamlet not only questions his responsibility to his father and duty to correct the state of Denmark, but also ponders over reasons this particular path has been laid out for him - - his fate. While he awaits the play, he is disillusioned on many levels. He wonders why it is that the people who sin are the ones who gain. His own uncle murdered his beloved Kind and father, and married his mother. Both women that are important to him, Ophelia and Gertrude, have turned away his love or betrayed him. The lies and heartache that fill Denmark are endless, and he questions the human condition. He wonders how Claudius can sin so readily, and also be living a perfectly contented life, yet it is he who must suffer through a painful fate. Hamlet does not wish to accept his fate at this point.
When Claudius is at prayer, Hamlet beings to accept his fate, but still ponders acting on it at that moment. Claudius brings so much sin into Hamlet's world that Hamlet refuses to allow Claudius to be forgiven for it. Hamlet witnesses all of Claudius" sins on a daily basis and wishes for him to pay for them.
