I have heard of Mithraism, Manichaeism, and the Sol Invictus cult. I have also considered Buddhism and Islam. What are some others I have not heard of?
To be fair, OP didn't say Christianity didn't exist, just that it is "replaced" which I assume means the position in the world it had and has today. By that logic, Islam could still come about.Without Christianity there would be no Islam either. But to answer your question, I think Zoroastrianism might be able to replace Christianity.
When you are saying replacing Christianity? I presume you mean after Christianity was established as the state religion of the Roman Empire and began to persecute the followers of the various polytheistic religions and stamp it out? Or do you mean if Christianity wasn't around which faith would take its role as the state religion which stamps out the polytheistic religions?I have heard of Mithraism, Manichaeism, and the Sol Invictus cult. I have also considered Buddhism and Islam. What are some others I have not heard of?
Remember we have to put our religious beliefs aside and think like secularist for the scenarios otherwise all what if Christianity never existed ei would be like it would since it was God plansI hate this cliche, Islam already codified as Isa(PUH)message failed at the time
Unfortunately, whatever Julian was trying to achieve, it was not appealing to neither Christians (of course) nor Pagans, just a limited circle of intellectuals close to him and even they were not completely on board with certain aspects of his faith. Honestly, ditch the whole "sacrifices are a must" and his attempts to replicate the hierarchy of the Christians and let them fight against each other (while completely revoking imperial patronage for the Christian clergy), focus on the positive aspects of the old religion (like games, celebrations, common meals etc.) and you might succeed in replacing Christianity without having to create a religious Frankenstein.That system that Julian the Apostate tried to introduce?
If Sabbatai Zevi hadn't recanted his own claim of being Messiah and let himself be martyred by the Ottoman Sultan, I honestly think that Sabbateanism could have repeated the history of the rise of Christianity and made the leap from a 'Jewish movement' and into an evangelical movement.
The Ottoman Empire saw itself as the successor of Rome, so having a new religion rise up and overtake the previous order, maybe even one day having a Sultan convert to the 'new religion' and see the rise of Sabbateanism in both the Ottoman Empire and then spread over the world.
Mormonism went from a handful of followers to several million in less than a century, Christianity itself went from a tiny cult in the middle of nowhere to the dominate religion of the Roman Empire in 2 centuries.Far too late. Christianity and Islame were already so established religion that even if Zevi would had beebn enough of courate to allow the sultan remove his head, his religion hardly would had been very succesful. There might be some millons of followers by 2022 but not anywhere near of Christianity nor Islam.