!!! POTENTIAL FLAMEBAIT. YOU HAVE BEEN WARNED. !!!
A scenario where Gautama Buddha becomes the great king he was prophesized to be had he not encountered any suffering (ITTL, he learns of suffering through books beforehand and seeing it in practice doesn’t really faze him), and Jesus succumbs to Satan’s third temptation on the mountain.
DISCLAIMER: I understand that this scenario is impossible under the teachings of just about every religion or lack thereof. This isn’t meant to be a serious what-if involving accurate portrayals of religious figures. It’s a silly map. Please don't post comments about religion. If I see any of them, I will turn off commenting.
It is the year 1894 since the Birth of the God-Emperor of Rome. The Heaven War is nearly entering its two thousandth year. Neither the Imperium of Rome nor the domains of the Great Siddhartha seem exhausted enough to surrender to their enemy. Countless billions have perished in the eternal battlefields of Eurasia. To forsake these souls, to throw their sacrifice away, would be the greatest sacrilege. And both sides believe that final victory is not only possible, but inevitable. After all, do they not have God on their side?
The Empire of Siddhartha is the older of the two, by about 500 years. Born into the Shakya clan, the great warrior-emperor Siddhartha united the territories around him and forged a powerful empire in northern India. While he was a strategic genius, Siddhartha was also aided by displays of supernatural power, such as driving horses and elephants of the opposing armies mad merely by staring at them, taking command of otherwise anarchic spirits and using them in his armies, and, in one infamous case, crushing an enemy king and his entire family beneath hundreds of pounds of flower petals. Siddhartha had an explanation for all of this: he was the ninth avatar of Vishnu. Any Hindu theologians and scholars who opposed the claim were either killed for their heresy by Siddhartha’s agents or spontaneously combusted while preaching to the masses.
Any question of Siddhartha’s otherworldly abilities dissapated as his rule extended from decades to centuries. While he did age, the ravages of time did not affect the great warlord like it did his subjects. Siddhartha was still fit enough to challenge the armies of Alexander the Great on the field of battle and drive him back into Persia, even though the Greek warrior had supernatural assistance of his own. Two hundred years after his ascension, Siddhartha had united the entire Indian subcontinent, and many throughout the eastern world worshiped him as a god.
While he was a warrior and an emperor, Siddhartha also fancied himself a philosopher of sorts. In his many years of rule, he had ample opportunity to think about the world. More pragmatically, Siddhartha saw the value in a unifying ideology, and realized that unless he was to take a more active hand in its development, the various religions arising around his persona could turn against him. To this end, he developed the Teachings of the Great Siddhartha, also known as Siddharthanism. Siddharthanism taught that, while the gods do exist, they are a force of nature like anything else, and can therefore be manipulated. Any man who reaches enlightenment becomes a master not only of the metaphysical, but also of the physical. Naturally, Siddhartha himself had reached ultimate enlightenment, giving him divine powers, and that he was the only individual who can reach ultimate enlightenment. Being the physical embodiment of [INSERT LOCAL POPULAR DEITY HERE] helps. However, the secrets of enlightenment were available to all who would devote themselves enough to self-sacrifice, meaning of course sacrifice to further Siddhartha and his empire. Those devoted enough to give their entire lives to the pursuit of enlightenment found themselves having some limited supernatural abilities, making them capable warriors and missionaries. The Siddharthans, naturally, have a holy mission to convert everyone on Earth to worshiping Siddhartha, so that all of mankind may be enlightened and reach a higher level of consicousness above the material.
Four hundred years after ruling his empire directly, Siddhartha retreated to the Himalayas in a quest to understand not only this world, but “all the other worlds.” Telling his closest aides that his brief psychic excursion beyond the confines of this world gave him glimpses of “horror beyond horror,” Siddhartha devoted his personal efforts to ensuring that the world does not succumb to such horrifying malevolence. He left governance of his empire to his most trusted subordinates, and it is his subordinates that rule to this day. Throughout the centuries, the Siddharthan Empire expanded voraciously, creating legions of converts whereever they did not outright conquer. The Turkish steppe nomads and the Chimu of the Furthest East ethusiastically adopted Siddharthanism, although with their own local flavor (believing that Siddhartha is an avatar of Tengri/their past emperors, or the other way around).
On the other side of the world, the Empire of Rome arose sometime after the collapse of Alexander’s empire. In their conquest of the Mediterranean, the Romans took control of Judea, the province where their eternal emperor would be born. As the son of a carpenter and an apocalyptic Jewish preacher, Jesus did not seem any more relevant than the multitude of other apocalyptic Jewish preachers. According to the Romans, what separated Jesus from the others is his divine origins and his decision to forge a deal with The Deceiver. The Deceiver promised Jesus all of the kingdoms of the world, if only he, the son of God, would bow. Jesus, knowing of his father’s plan to sacrifice him for the sake of the ungrateful humans, agreed, for the meanwhile.
This agreement worked: when Jesus was crucified after the Romans arrested him for attempted insurrection, he rose from the dead to lead the rebellion anew. Try as they might, the Romans could not strike him down in battle, and many legions turned to worshiping him after defeat. Great displays of supernatural might, such as burning his enemies with sunlight as the symbol of his name blazed on its surface, helped change minds very quickly. With his growing army, Jesus marched on Rome and took the great city, proclaiming himself Emperor of Rome, Sol Invictus, Incarnation of Jupiter, Usurper of Yaweh, and other titles, adding more as his empire grew.
Like his rival to the east, Jesus’ clear supernatural abilities won him many followers. Unlike Siddhartha, Jesus was far less tolerant of belief in other gods, and preferred instead to prove his divinity and power over “false gods” either through personal appearance or “miracles” that his missionaries could perform. On the other hand, Jesus encouraged the practice of “Romanizing” local beliefs, placing himself in place of traditional deities and assuming their identities. The Vesperian Despotate, originally a Norse colony, still worships Jesus as the Allfather, the most powerful member of their pantheon, and the Khwesao worship him as the Great Ancestor of Man, the one human from whom all other humans are descended.
The Roman Imperium’s official religion venerates Jesus as the Son of Man, the liberator of humankind from Yaweh, the abusive creator god and Jesus’ father. Through a Faustian pact, Jesus broke mankind away from Yaweh’s influence and has taken his rightful place as ruler of all mankind. All humans have a duty to obey Jesus and expand his empire’s domains to cover the entire planet, so that humankind can enter an era of peace and progress. Peace, Jesus teaches, can only be reached through power.
The Deceiver, or Satan, was originally venerated in Rome, but was later denounced by Jesus, who added “Conqueror of the Deceiver” to his list of titles. This had very negative consequences for Jesus: an avatar of the Deceiver appeared to take away his power, and while Jesus successfully defeated the Deceiver and took control of his forces in the material universe, Jesus was mortally wounded. In a state of near-death, Jesus was interred in a magically-infused sarcophagous to preserve him from death, allowing him to bind the Deceiver’s demons to Roman command. Jesus is still Emperor of Rome, but the day-to-day rule of the Roman Empire fell to the Senate.
The Holy Roman Imperium and the Siddharthan Empire first clashed in Persia in the early 300s, when the Imperium tried to destroy the heretical Zoroastrians once and for all. The Heaven War, as it was called, continues well into the 19th century. While there have been significant lulls in the fighting, peace has never been officially declared. Technological innovations never gave one side such a great advantage that they could defeat the other, leading to a millennia-long stalemate in Central Asia and Persia. Elsewhere in the world, wherever the Roman and Siddharthan empires touch, an eternal battlefield arises.
But there are countries outside the orbit of either theocracy. In the far east, the Chinese and Yamato have resisted all attempts by the Siddharthans to subjugate them. The Chinese have historically credited this to the power of their ancestors, although the current atheistic government attributes this to a more psychological “national spirit of autonomy and independence” and a greater population. The modern Chinese deny the existence of gods, believing the demons they face on the battlefield are merely extraterrestrial beings somehow under the employ of their enemies, and that the miracles of Siddhartha and Jesus are myths fabricated by both empires to better control their population. The Yamato, on the other hand, are very religious, and believe that the kami which protect their domains are responsible for their continued independence. On the other side of the world, the Mexica have successfully resisted repeated Roman attempts to subjugate them through the use of blood magic. Called Servants of the Deceiver by their Roman enemies, the Mexica do make heavy use of human sacrifice, and some of the creatures serving in their armies are even more alien than the demon legions of Rome. These neutral powers want little to do with the Heaven War, although as the two superpowers decay, the neutrals’ ambitions rise. The Heaven War may soon have a third, independent faction joining the fray.