Since Christianity is one of the world's largest and most pervasive religions, it should come as no surprise that one of its central tenets is featured in many works of fiction: the concept of a Heaven and a Hell, forever in opposition to one another. This doesn't mean that the works have to represent both sides in strictly biblical terms (or even name them as such), but should follow the traditional depiction of both sides.
One of the most common ways this appears is having the central plot resolve around an actual physical battle being fought between the two forces, usually The Armies of Heaven versus The Legions of Hell. Typically, this battle is being fought in secret while the rest of the world goes about their "happy" lives. The motives of both may differ slightly from work to work, but it generally revolves around wanting to Take Over the World. If this conflict does spill out into the world at large, you may be dealing with Hell on Earth or even Hell Invades Heaven. Granted, this conflict is typically a metaphor for Order Versus Chaos, but occasionally works will depict both sides as flawed or undeserving. Angels, Devils and Squid is a variation of the conflict that adds a third dynamic to the typical "good versus evil" conflict, by introducing a chaotic, alien element that often just wants to obliterate everything based on a Blue-and-Orange Morality.
While the central conflict has its roots in Christian dogma (which actually got it from an older religion, Zoroastrianism, through its Jewish ties), and may even use names, places, and ideas straight from The Bible, expect the works to twist the concept to fit the storyline or the themes of the work. Also, expect lots of quotes straight from the good book and lots of traditional depictions of angels and demons.
Compare Order Versus Chaos, Powers That Be, Harmony Versus Discipline, Balance Between Good and Evil, Light/Darkness Juxtaposition. For a battle between different Gods within or between pantheons, see Divine Conflict.
- Dogma: subverts this as Hell has as much reason as Heaven to stop the 2 rogue angels from getting back into Heaven, as Satan does not want to see another succeed where he failed. The one behind the whole scheme would rather have Cessation of Existence over the eternity of Hellfire he was punished with over not choosing a side (though he would have received the same fate for not choosing the 'correct' side) during the original war in heaven.
- The Exorcist: With the priests representing the forces of Heaven, the battle is particularly vivid here.
- Little Nicky: Not much violence between the two forces, but the battle is there none-the-less. A rare example where Hell is depicted as, at least somewhat, noble.
- Constantine (2005) deals extensively with the battles of Heaven and Hell and how the titular character is mixed up in them.
- Wendy Alec's Chronicles of Brothers series is an imaginative expansion of the Bible story concerning the fall of Satan and the ongoing war between Heaven and Hell that will resolve itself in the (interpreted) events of Revelation. Ms. Alec is scrupulously diligent in sticking absolutely to the script as Fundamentalist American Christian theology interprets it - Rapture and all - and even though her books are essentially Christian polemic and we all know what way the script is intended to end, contrives to create a readable and engaging story.
- The Dresden Files: While Harry does his best to avoid confrontations between the fallen and the faithful the angels are the most powerful beings he's properly encountered and the fight between the divine and the infernal is constant and Harry is good friends with the Knights of the Cross. Angels are on the side of free will and human determination which makes it near impossible for them to properly interfere in things as doing so will cause them to fall, though there are loopholes they happily use. The fallen posses humans and lie to them for their own ends.
- Terry Pratchett and Neil Gaiman's Good Omens is a beautifully subversive take on the idea of Heaven versus Hell, seen through the eyes of an Angel and a Demon who are fated to be on opposite shoulders of the human race - for eternity. However, there is still a conflict between the Angels of Heaven and Demons of Hell, but they can get along well enough when their goals align, such as the preparation of the final war between the two.
- Adam R. Brown's Astral Dawn features an epic war between the forces of Heaven and Hell, though they are typically referred to as Averya and Nazyra. They are the same places, however, as it is established the same places spoken of in the Holy Bible are known by many names.
- Tolkien's Legendarium does not have a traditional Heaven or Hell, but the celestial creations of Eru Illuvatar, the Ainur, can be divided into the Forces of Good and the Forces of Evil, the latter being those fallen Maiar (lesser celestials) who have followed the fallen Valar (higher celestial) Morgoth in his ways. Thus, any fight between these beings fits the trope. Gandalf's battle against the Balrog, mostly an Offscreen Moment of Awesome in the books but depicted onscreen in the Peter Jackson films, comes to mind.
- Played straight in Good Omens (2019). Heaven and Hell want to start the Apocalypse in order to settle their differences. Angel Aziraphale and demon Crowley are not amused.
- In Supernatural, the war between demons and angels became a major plot point eventually and was a case of Black-and-Gray Morality. The demons, led by the Fallen Angel Lucifer, are clearly evil and seek to wipe out humanity, but it turns out that Heaven's leadership has allowed for Lucifer to be set free so that Michael can defeat him in the final battle, no matter how many humans (or angels) get killed in the crossfire.
- This is actually an Unbuilt Trope in Christianity itself- turns out, it's pretty hard to have a war when one side is omnipotent. Every time demons and angels- or worse, demons and God- fight in the Bible, it's every bit the Curb-Stomp Battle for the forces of good you'd expect. In broader Christian teaching it's generally accepted that demons only "fight" heaven because God gives them permission to, and any time He wants He could just destroy them. Come the end times, He'll just win the whole war with a metaphorical snap of His metaphorical fingers.
- Exalted initially had this as a fairly minor plot point- Hell exists and hates (personally) Heaven, but has been defeated so thoroughly that it's not able to do anything beyond sending the odd demon through on Calibration. However, over the course of the second edition, the Infernal Exalt and the Yozi's attempts to regain control of Heaven became more and more central to the Meta Plot (for better or worse). In third edition, it's back to a minor background detail, with the Yozis sending demons and exalts out for proxy revenge rather then posing an existential threat.
- In Nomine is centered entirely around this, being set the cold war between Heaven and Hell as they work to push humanity towards its best or worst state without triggering Armageddon. By default Heaven is Good, but not perfect and not united, while Hell is Evil but not every demon personally is. However, there are alternate frameworks presented too.
- KULT has the subtle conflict between the Archons and Death Angels over rulership of humanity. As befitting Kult, both sides actively hate us- the main difference being that the Archons want us as mindless sheep while the Death Angels want us in unending agony- and both factions fight among themselves as much as their nominal enemies. And neither want us to realize what's really going on...
- The Bayonetta series follows the conflict between the various forces of the "Trinity of Realities", Paradiso (Heaven), Inferno (Hell) and the human world. While the Umbra Witches and Lumen Sages are forces of the human world, they are aligned with Inferno and Paradiso respectively. In the first game, Bayonetta fights angels and even travels to Paradiso for a few levels, while in the second game she also travels to Inferno and fights demons.
- Diablo: The entire conflict of the story is a battle between the High Heavens led by the Angiris Council and the Burning Hells led by the Seven Great Evils. Ongoing for eons following the deaths of the prime good and evil entities, Anu and Tathamet, it was mostly a stalemate, with neither side ever able to clinch a victory due to their various foibles. With the creation of the mortal world, Sanctuary, by a group of renegade angels and demons working together, the nature of the conflict changed. The Sin War has now been ongoing for a few millennia, in which either side attempts to sway the inhabitants of Sanctuary indelibly to their favor, knowing that whichever side controls the world completely will have a decisive advantage.
- Disgaea: Hour of Darkness: The central conflict again. Slightly less dogmatic than other versions. A Batman Gambit done by the benevolent leaders of both eventually succeeded in uniting the two.
- Subverted in Doom Eternal. While you would expect the angelic Maykrs to be battling the demons of Hell alongside the Slayer, it turns out that they're not only not doing squat about the situation on Earth, but they're actively helping the demons because their leader, the Khan Maykr, made a deal with the Dark Lord that leads the demons to hand over worlds for the demons to devour in return for the Argent Energy that their world of Urdak requires to survive — energy that turns out to be made of the horribly tortured souls of Hell's victims. But when the Khan Maykr brings the Icon of Sin to Urdak, the Maykrs' Heavenlike homeworld to awaken it and bring it to heel so she can unleash it upon Earth and complete the destruction of humanity, it results in a full scale demonic invasion of Urdak that, once the Khan Maykr is slain by the Slayer, the other Maykrs are ill-equipped to stop.
- Most of the plot of both Nexus War games revolves around the battle between the angels of Elysium and the demonic hordes of Stygia. There are several neutral free-will-aligned deities around as well to make for a Mêlée à Trois, but the main focus of the lore is on heaven vs. hell.
- In Chapter 7 of Super Paper Mario, an army of Skellobits from the Underwhere (Hell) invades the Overthere (Heaven), and fights Nimbis there. The Skellobits come very close to succeeding. An actual battle between the forces is seen in-game.
- Lioden: The October Event involves a fight between the armies of heaven and hell. The player is given the option to join either side and fight angels or demons... or ignore it altogether and focus on the other supernatural events going on.
- South Park has very unique versions of heaven and hell. Nearly everyone goes to Hell except for those belonging to one religion, so Gandhi, Hitler, John F. Kennedy, and Ted Bundy are all in the same place. Satan is Affably Evil and enjoys throwing big parties. Up above, God is a bunyip who rules over a Fluffy Cloud Heaven. The residents of Heaven are Mormons and Sadaam Hussein (although he was sent there as a punishment). However, God can change the rules so more people can be allowed in. The person who gets to the highest level in "Heaven vs. Hell" for the PSP on Earth is selected to lead the armies of Heaven against The Legions of Hell, but must not be revived in any manner. God created the PSP for this purpose; the individual uses a Golden PSP to do this for real and is referred to as "our Keanu Reeves."