Which fatal flaw leads to Hamlet's catastrophic downfall?

Shakespeare's enduring play Hamlet, revolving around a philosophical protagonist, explores the most complex forces of humanity and takes the concept of revenge to a new dimension. Prince Hamlet's character is many things: a scholar, speaker, actor, prince. He shows greatness in all his activities, save one: his inactivity. Hamlet's one most fatal flaw is his ability to reconcile the differences between his moral sensitivities and his primary task to avenge his father. This delay in judgement allows Claudius to inevitably escape revenge and plot Hamlet's ultimate defeat. A major part of Hamlet's uncertainty is the fact that death is so permanent and there are no means of escape. He is bewildered that people would "rather bear those ills we [they] have,/Than fly to others that we know not of../Thus, conscience makes cowards of us all: (III, I, 81-83). He questions why people would suffer from life's current burdens and not rid of it through death instead, only as they lack knowledge of what death has to offer. Life and death perplex Hamlet and gives him cause to think upon the morality his actions. This contemplation, however, also helps persuade Hamlet against performing the murder upon his uncle. Throughout the play, there were numerous opportunities for Hamlet to avenge his father through the death of King Claudius; but Hamlet was too melancholic and indecisive, to kill his uncle. His best opportunity to fulfil his self-obligatory task, occurred whilst King Claudius was "in his retirement" (III,II, 288), kneeling at the prayer, "distempered" (III, II, 288) and vulnerable. Hamlet, however, wastes this opportunity and reasons instead that murder committed himself goes against his and God's will, albeit against his father's honour and vengeance. Hence, Hamlet's strong religious bonds is another fatal flaw, causing him to prolong this sinful deed. Hamlet finally receives the justifying reason for the King's defeat when he reflects upon Young Fortinbras of Norway's actions, who similarly acts to avenge his own father. A third time Hamlet dithers over life and death occurs when Fortinbras of Norway