Why did Hamlet delay killing Claudius in act 3 scene3?

In act 3 scene 3 of Shakespeare's Hamlet, Hamlet delays killing Claudius because Claudius is at prayer. Throughout the play, Hamlet wrestles with the moral implications of killing Claudius and struggles with his desire for revenge.

In this particular scene, Hamlet finds Claudius alone and vulnerable, but chooses not to kill him at that moment because he believes it would be wrong to do so while he is praying. Hamlet argues that if he kills Claudius while he is praying, Claudius' soul would go straight to heaven, and Hamlet would be just as guilty of sin as Claudius is. Instead, Hamlet decides to wait for a moment when Claudius is not at prayer, so that he can ensure that Claudius' soul goes to hell where he belongs.