Emperor and Galilean is a very significant Ibsen work, despite its lack of fame. It is the last of his epic works and his last historical play. It is autobiographical and the clearest summation of his opinions on religion. Ibsen himself said that it was his masterpiece.
For all those reasons, I am disappointed that I don't like it more. However, there is still much of interest within the play.
For his last historical play, Ibsen turns away from Norwegian history and back to Roman history, the subject of his very first play, Catiline. Catiline felt like reheated Shakespeare, and Emperor and Galilean clearly owes a debt to Shakespeare too.
There is a scene where Julian uses duplicitous eloquence to win over the soldiers, reminiscent of Mark Anthony's crowd-pleasing speech in Julius Caesar. Julian resembles Hamlet in the early acts, living in fear at a hostile court, before turning into MacBeth by the play's end, the ruler taking power by force and maintaining himself by oppression and tyranny.
However, Ibsen's play is a long way from Shakespeare in other respects. Like Catiline (and Earl Skule), Julian is another rebel who yearns for leadership. Of course, most of Ibsen's heroes are rebellious or iconoclastic. The political rebels are generally marked by vacillation and self-doubt, and perhaps that is why all three of these heroes are doomed to fail. In Julian's case, he does at least become Emperor, but is unable to impose the old Roman religions over his subjects, or to defeat the new Christian religion, finally dying at the hands of a fanatic.
The Wikipedia page provides a link to a rather poorly-written review which suggests that Emperor and Galilean may have influenced Hitler's behaviour. However, the argument is rather tenuous, since it assumes that Hitler was so besotted by the work that he even copied Julian's mistakes.
I mention this only because it does raise a troubling aspect of Ibsen's work. Ibsen often does seem to be enthusiastic about the strong hero who triumphs by an act of will. Weaker characters are pitiful and end up crushed and left by the wayside. I often wonder what Ibsen would have made of Hitler. Would his awe for powerful strong-willed characters have swayed him into unwise sympathy for the Nazi leader, or would Ibsen's more liberal tendencies have alienated him from the Third Reich? I guess we will never know.
However, the political intrigues in Emperor and Galilean are far less interesting than the religious discussions. Julian hesitates between two religions - the Roman religion of the past which promises joy and happiness, though perhaps of a shallow kind, or the new sober Christian religion which is intolerant and celebrates death, rather than life.
This is a debate that Ibsen will be having with himself throughout the rest of his plays. How to balance our sense of duty and seriousness with finding a joy for living? The two aspects are memorably captured in a scene where a procession of revellers from the old religion clash with a procession of prisoners from the new gloomier religion:
Apollo Procession (sings): Blessed to be cooled by a garland of roses/Blessed to be warmed by the light of the sun!
Prisoners: Blessed to die in a blood-filled grave/Blessed to enter the garden of heaven
We are left in no doubt of what Ibsen thinks of Christianity in the first scene where the Christians are seen bullying members of the older religion. Later, Julian is repelled by their humbug when they proclaim miracles from the body of his adulterous wife, and he chooses the older religion. He is doomed to fail. His attempts to live peaceably with the Christians are thwarted by their dogmatic acts of terror, and his attempts to repress them only make them stronger. Ultimately, it is their religion that will triumph.
However, the play discusses the idea of forming a new religion that will replace both. Julian fails because he wishes to return to the infantile older religion based purely on pleasure, rather than seeking to marry the best parts of both religions and form a new kingdom. This appears to be what Ibsen is looking for too.
The double-play is overlong and does not add up to Ibsen's best work, but at this stage of his career, Ibsen was incapable of writing something that was not immensely interesting.