At the start when Pentheus enters he declares that he has heard rumours that this new god is driving the women to leave their homes and have criminal actions. He says his worshippers are frolicking and satisfying the lusts of men. He is basing these blames purely on rumour and even calls Dionysus a parvenu god. He is not respecting the new god and even though he knows the gods can punish humans, he still refuses to worship him; he even states that he will leave him out of his worship when he goes to sleep.
He calls him some foreigner and disrespects him by saying he is a wizard conjuror and had fragrant golden curls, not meaning to compliment him but insult him. Here perhaps he does deserve his punishment because he is disrespectful and unkind to the new god because he is a cynical ruler. Cadmus and Tiresias encourage Pentheus to allow Dionysuss worship into the city but here will listen to none of it and he is rude to both of them (which again, is not expected of a king but his pride and arrogance overpowers his respect for his elders).
He has absolutely no piety towards Dionysus and insults him once he is brought (in disguise) to Pentheus. He is given many warnings by Dionysus but Pentheus chooses not to hear then and ignores him, he is spoken to in riddles but Pentheus once again shows no understanding and Pentheus even goes as far as mocking Zeus and this makes us pity him because he does not understand what is going on. In this instance I do not believe he deserves his punishment. He doesnt believe in Dionysus and his obsession with order proves his downfall, in spite of the warnings he is given.
Later in the play Dionysus has the upper hand by hypnotising Pentheus and forcing him to see a bull and trying to tie it up. Here we begin to feel sorry for Pentheus and think that it is cruel of Dionysus to trick him. There is a contrast between the rage and frustration of Pentheus and the calmness of Dionysus. A herald comes and tells Pentheus about the worship of the Bacchants and Dionysus is quick to trick him to witness it himself, he is lured like a child and is easily persuaded by Dionysus because he is still hypnotised by him.
Because he becomes so child-like and vulnerable our pity for him increases because he is unable to control his actions from here on. I do not believe he deserves his fate now because he is lured by Dionysus charm and he has put all of his trust into the gods hands. We feel sorry for Pentheus here and because he is more innocent here (is persuaded to dress up as a bacchant) and does not deserve this cruel punishment Dionysus has planned for him.
Dionysus now becomes the cruel one and plays with Pentheus vulnerable state and mentions sick jokes towards his death by saying you shall ride home¦ in your mothers arms. Which is terrible dramatic irony and we are forced to feel compassionate towards Pentheus because we know exactly what is going to happen to him. Because it is his mother that is going to kill him, I believe he does not deserve to be killed like this, but by his mother killing him it forces us to take more pity on Pentheus and Agave and I do not believe he deserves his punishment like this.
It just proves the malice of Dionysus and how far he will go to induce punishment on the city of Thebes in order to be worshipped. So Pentheus deserves his punishment because he was unwilling to accept a new god and refused to worship someone he did not believe in and this resulted in his death but he did not deserve the way in which he was punished because it was his mother who was forced to do it and he was brutally ripped apart while in a child-like state of mind and under Dionysus control. So we feel sympathy towards him and I do not believe he deserved his punishment