If Buddhism is just a philosophy, why does it have a punishing Hell?
 
According to the scriptures of Buddhism everyone who falls into hell is tortured with all of the punishments: some of the tortures are skipped; in some cases the hell-being’s kamma is exhausted before the full round of tortures is completed, so that he dies and is reborn elsewhere; and not everyone goes for repeated rounds. Also, we should note that punishment in hell is not for an eternity. As the discourse implies, when the hell-being’s bad kamma is exhausted, he dies and is reborn elsewhere, in accordance with his remaining kamma.
 
Here is a part of the, “Devaduta Sutta: The Deva Messengers.”
 
Translated from the Pali, (The earliest written scriptures of Buddhism are collected in the Tripitaka, also called the Pali Canon).
 
That evil kamma was done by you yourself, and you yourself will experience its result.’ “Then the hell-wardens torture [the evil-doer] with what’s called a five-fold imprisonment. They drive a red-hot iron stake through one hand, they drive a red-hot iron stake through the other hand, they drive a red-hot iron stake through one foot, they drive a red-hot iron stake through the other foot, they drive a red-hot iron stake through the middle of his chest. There he feels painful, racking, piercing feelings, yet he does not die as long as his evil kamma is not exhausted.
 
“Then the hell-wardens lay him down and slice him with axes. Then they hold him feet up & head down and slice him with adzes. Then they harness him to a chariot and drive him back & forth over ground that is burning, blazing, & glowing. Then they make him climb up & down a vast mountain of embers that is burning, blazing, & glowing. Then they hold him feet up & head down and plunge him into a red-hot copper cauldron that is burning, blazing, & glowing. There he boils with bubbles foaming. And as he is boiling there with bubbles foaming, he goes now up, he goes now down, he goes now around. There he feels painful, racking, piercing feelings, yet he does not die as long as his evil kamma is not exhausted.
 
“Then the hell-wardens throw him into the Great Hell. And as to the Great Hell, monks:
 
It’s four-cornered & has four gates
set in the middle of each side.
It’s surrounded by an iron fortress wall
and roofed with iron.
Its floor is made of red-hot iron,
heated, fully blazing.
It stands always, spreading 100 leagues all around.
 
“The flame that leaps from the eastern wall of the Great Hell strikes the western wall. The flame that leaps from the western wall strikes the eastern wall. The flame that leaps from the northern wall strikes the southern wall. The flame that leaps from the southern wall strikes the northern wall. The flame that leaps from the bottom strikes the top. The flame that leaps from the top strikes the bottom. There he feels painful, racking, piercing feelings, yet he does not die as long as his evil kamma is not exhausted.
 
“There comes a time when, ultimately, with the passing of a long stretch of time, the eastern gate of the Great Hell opens. He runs there, rushing quickly. As he runs there, rushing quickly, his outer skin burns, his inner skin burns, his flesh burns, his tendons burn, even his bones turn to smoke. When [his foot] is lifted, he is the just same.  But when he finally arrives, the door slams shut. There he feels painful, racking, piercing feelings, yet he does not die as long as his evil kamma is not exhausted.
 
“There comes a time when, ultimately, with the passing of a long stretch of time, the western gate of the Great Hell opens… the northern gate… the southern gate of the Great Hell opens. He runs there, rushing quickly. As he runs there, rushing quickly, his outer skin burns, his inner skin burns, his flesh burns, his tendons burn, even his bones turn to smoke. When [his foot] is lifted, he is the just same. But when he finally arrives, the door slams shut. There he feels painful, racking, piercing feelings, yet he does not die as long as his evil kamma is not exhausted. 
 
“There comes a time when, ultimately, with the passing of a long stretch of time, the eastern gate of the Great Hell opens. He runs there, rushing quickly. As he runs there, rushing quickly, his outer skin burns, his inner skin burns, his flesh burns, his tendons burn, even his bones turn to smoke. When [his foot] is lifted, he is the just same. He gets out through the gate. But right next to the Great Hell is a vast Excrement Hell. He falls into that. And in that Excrement Hell needle-mouth beings bore into his outer skin. Having bored into his outer skin, they bore into his inner skin… his flesh… his tendons… the bone. Having bored into the bone, they feed on the marrow. There he feels painful, racking, piercing feelings, yet he does not die as long as his evil kamma is not exhausted.
 
“Right next to the Excrement Hell is the vast Hot Ashes Hell. He falls into that. There he feels painful, racking, piercing feelings, yet he does not die as long as his evil kamma is not exhausted. 
 
“Right next to the Hot Ashes Hell is the vast Simbali Forest, [with trees] reaching up a league, covered with thorns sixteen fingerbreadths long — burning, blazing, & glowing. He enters that and is made to climb up & down them. There he feels painful, racking, piercing feelings, yet he does not die as long as his evil kamma is not exhausted. 
 
“Right next to the Simbali Forest is the vast Sword-leaf Forest. He enters that. There the leaves, stirred by the wind, cut off his hand, cut off his foot, cut off his hand & foot, cut off his ear, cut off his nose, cut off his ear & nose. There he feels painful, racking, piercing feelings, yet he does not die as long as his evil kamma is not exhausted. 
 
“Right next to the Sword-leaf Forest is the vast Lye-water River. He falls into that. There he is swept downstream, he is swept upstream, he is swept downstream & upstream. There he feels painful, racking, piercing feelings, yet he does not die as long as his evil kamma is not exhausted. 
 
“Then the hell-wardens pull him out with a hook and, placing him on the ground, say to him, ‘Well, good man, what do you want?’ He replies, ‘I’m hungry, venerable sirs.’ So the hell-wardens pry open his mouth with red-hot iron tongs — burning, blazing, & glowing — and throw into it a copper ball, burning, blazing, & glowing. It burns his lips, it burns his mouth, it burns his stomach and comes out the lower side, carrying along his bowels & intestines. There he feels painful, racking, piercing feelings, yet he does not die as long as his evil kamma is not exhausted. 
 
“Then the hell-wardens say to him, ‘Well, good man, what do you want?’ He replies, ‘I’m thirsty, venerable sirs.’ So the hell-wardens pry open his mouth with red-hot iron tongs — burning, blazing, & glowing — and pour into it molten copper, burning, blazing, & glowing. It burns his lips, it burns his mouth, it burns his stomach and comes out the lower side, carrying along his bowels & intestines. There he feels painful, racking, piercing feelings, yet he does not die as long as his evil kamma is not exhausted. 
 
“Then the hell-wardens throw him back into the Great Hell once more.
 
“Once, monks, the thought occurred to King Yama: ‘Those who did evil actions in the world are tortured in these many ways. O that I might gain the human state! And that a Tathāgata — worthy & rightly self-awakened — might arise in the world! And that I might attend to that Tathāgata! And that he might teach me the Dhamma! And that I might understand his Dhamma!’ 
 
“I tell you this, monks, not from having heard it from another contemplative or brahman. On the contrary, I tell you this just as I have known for myself, seen for myself, understood for myself.”