As I mentioned when talking about The Later Roman Empire, historians of the fourth century spend an inordinate amount of time on the emperor Julian, because the sources for his life are unusually good. This book is a good example: it’s a biography of Julian.
Of course, the other reason that Julian is interesting is the big “what if?” that he raises. As a committed pagan emperor, could he have reversed the Christianisation of the Roman Empire? It’s an interesting question, because the answers are not obvious either way.
Julian was a talented leader, with a fair amount of military talent, wide reading, and a good head on his shoulders. He was also fully capable of alienating large numbers of people through tactless political goofs; after becoming emperor, he appointed a Gaul he trusted to high office, which alienated the Senate. He would never have made a democratic politician, but he wasn’t asked to. He got to be an autocratic ruler.
The evidence is that he would not have endorsed a full-on persecution of the Christians; he doesn’t seem to have gone for that sort of thing. However, he would have restored pagan temples, knocked down some churches, and he did forbid Christians from teaching the normal school curriculum of rhetoric. More important, paganism would have been in favour. There would have been new temples, pagan rituals would have been restored to public life, and pagan philosophers would have had the whip hand in challenging the Christians. This all suggests that he could have reversed the trend.
On the other side, his personal version of paganism was rather eccentric. Even his friends and supporters thought that he was a bit too into sacrificing hundreds of animals to the gods. He was also, it seems, a devotee of the Unconquered Sun, although he was a henotheist rather than a monotheist. That is, Julian’s paganism did not connect to the religiosity of most people in the empire. It might have been doomed to die with him, just like Akhenaten’s religious reforms did in Egypt.
The question is purely academic because he miscalculated badly, getting into a war in Iraq and dying on the battlefield after only eighteen months as emperor, without a clear heir. (Back then, leaders who took their nations into disastrous wars tended to die in battle. It is notable that this doesn’t seem to have stopped them.) In the end, then, he is almost completely irrelevant to the course of history. The interest is that he might not have been, and this book, which is, after all, one of my main sources for what I know about Julian, is a good account of him as a fully rounded individual, drawing on multiple sources. I recommend it.