Though it’s always up for debate, we can say that a fair amount of Gore Vidal's historical novel Julian is accurate, and some of it is just Vidal's imagination at work.

One part that corresponds to generally accepted history is Julian’s resistance to Christianity. Though Julian was raised Christian, the violence and intense arguments that it caused led him to condemn Christianity and embrace a kind of paganism.

In the novel, Vidal includes Julian's opposition to Christianity. We see the Christian religion referred to as a "death cult" and a Christian church called "a charnel house."

Though, we should be open to the idea that Vidal is playing up Julian's opposition to suit his own modern ideas about Christianity.

Another area of the novel where the story adheres to accepted history is Julian's prowess regarding military campaigns. In real life, Julian achieved impressive victories over early German tribes. These remarkable wins are related in Vidal's novel.

As in real life, in Vidal's novel, Julian wages one military campaign too many, which results in him receiving a deadly wound.

Sex is one area where Vidal likely used his imagination more than real-life accounts. The sex acts Vidal writes about might be nearly impossible to verify using scholarly sources and methods.

You might want to think about why one reviewer decried Vidal's sex scenes as "disgusting enough to sicken the reader."