Julian's efforts to restore and put new life into paganism are much more interesting than his attempts to damage Christianity.  He called the religion he had so fervently adopted Hellenism, and his co-religionists Hellenes: Christianity was a barbarian cult, its supporters Galilaeans.  But in reality the Christianity of the fourth century had absorbed much of what was best and most enduring in Hellenism; while the religion of Julian drew more of its contents from Oriental than from Hellenist sources.  One cult into which he had been initiated and which he greatly esteemed, Mithraism, was the only one of those Oriental religions which seems to have been entirely unaffected by Hellenist thought.

The religion which Julian attempted to force on the Empire was a mosaic of decadent philosophy, bloody sacrifices, rituals old and new, “spiritualism” and divinations of all sorts.  Its piety came from the cult of the Mysteries.  It contained so much that was new that it was much more an attempted reconstruction or reformation than a revival of paganism.

Julian was quick to see that no religion could be universally accepted which had not behind it some common stable truths, and that Christianity had gained enormously from that compact system of doctrine which it had laboriously built up during the three centuries of its existence.  If critics, like Celsus, had made capital out of the intellectual differences within Christianity, paganism was in a worse case.  Heathenism had no basis of intellectual certainty; it had no universally accepted or acknowledged system of doctrine.  If pagan philosophy were appealed to, it was anything but an harmonious system — one teacher said one thing only to be refuted by another.  The Hermotimus of Lucian had somewhat wickedly shewn that the opinions of philosophy were as various as the thinkers were numerous.  But the philosophic thinking of the age of Julian was eclectic, and Neoplatonism was supposed to reconcile all sorts of opinions.  By ignoring some and rounding off the sharp corners of others it might be plausibly made out that all philosophies really meant to say the same things if they were only rightly understood.  So Julian went to Neoplatonism for the intellectual basis or dogmatic theology of his new catholic State Religion.  His philosophical acumen was by no means equal to that of his masters and he modestly confessed it.  Iamblichus had taught him all that he knew, and that philosopher, in the opinion of Julian, had so explored the heights and depths of human and divine thought that nothing remained for any man save to accept his conclusions.  The Neoplatonic thought of a Trinity of existence took the central place of the Christian in this new pagan theology.

Three worlds exist.  First and highest is the realm of pure ideas where the Supreme Principle, the One, the Highest Good, the Great First Cause, lives and reigns.  Below it is the intellectual world over which presides the same Supreme Principle, but now represented by an emanation from Itself, wholly spiritual, the Logos of the Platonic philosophy.  The third is the world of sense existence, the universe of things seen and handled, and there, as beseems its surroundings, the ruler, the emanation from the Supreme Principle, assumes a visible form and can be seen while adored.

The “common man,” of course, could not be expected to understand or care for such high matters; but pagan philosophy had never thought much of the “common man” (which was its weakness), and he had always the gods nearest him to worship in that instinctive way which was alone possible for an intelligence such as his.  Yet, Julian, with more sympathetic feeling for his needs than most pagan thinkers, made provision that even he should be taught the underlying unity and catholicity of his ancestral faith.  Just as in Christianity, Jesus was the revealer of the Father, and men were taught to see the One Supreme God in the Son Incarnate, the Mediator, so Julian called on all men to see in the great orb of day the visible manifestation of the Supreme Principle, the First Cause, Who has begotten him and placed him in the heavens, the medium through which He dispenses His benefits throughout the universe of men and things.  Even Christians, Julian thinks, might come to see this if their minds were not so darkened.  They believe in Jesus, whom neither they nor their fathers have ever seen; but they do not believe that the God Helios is the true revealer of God, Helios whom the whole human race from the beginning of time has seen and has honoured as their munificent and potent benefactor, Helios the living animated beneficent image of the Supreme Father, Who is exalted above all the powers of reason.  Man has body as well as soul, he has senses as he has capacities for intellectual thinking, therefore he needs visible gods to represent the gods invisible whom the Supreme Principle has sent forth from Himself and who suit the religious needs not merely of the different nations and tribes of mankind but also of the various divisions of men such as shopkeepers, tax-gatherers, dancers, etc.  These thousands of deities are all in their places representatives of the One Supreme Principle, Who has sent them forth and on Whom they depend.  The sun among the stars is an emblem of this divine unity in diversity.

Having thus demonstrated, as he believed, by exhortations and treatises, the unity which underlay the surface diversity of polytheism, Julian gave full scope to his desire to honour every manifestation of the one Supreme Principle, and to make use of every means whereby man could both shew his reverence for and seek communion with the divine.  His first care was to make it clear to all that the worship of the old gods was to be the privileged cult.  Bishops were banished from the antechambers and audience halls of the palace and in their stead came pagan priests and Neoplatonic philosophers — chief among them being Maximus the “medium.”  The Emperor was unwearied in issuing decrees that all the ancient temples were to be thrown open and that the ceremonies of all the ancient cults were to be duly performed.  It might be said that he converted his palace into a temple — so determined was he that every heathen festival should be observed and every detail of appropriate rite and sacrifice duly attended to — and it was said that his knowledge of the various rituals surpassed that of the priests themselves.  His devotion to the whole sacrificial system of paganism has been recorded both by enemies and friends.  We are told of one solemn sacrifice at which the victims included one hundred bulls, rams, sheep and goats, as well as innumerable white birds from land and sea.  He issued minute directions about the number of the sacrifices which were to be offered by day and by night in the reopened temples.  He wished that all the old gods should be invoked — Saturn, Jupiter, Apollo, Mars, Pluto, Bacchus, Silenus, Aesculapius, Castor and Pollux, Rhea, Juno, Minerva, Latona, Venus, Hecate, the Muses, etc. etc.; but personally, like the pagans of the age he lived in, he was more devoted to the deities of Oriental origin — to the Attis cult, to Mithras, and most of all to Isis and Serapis.  Dionysos, whose cult had many of the Oriental characteristics, seems to have been his most favoured among the gods of Greece.

The office of Pontifex Maximus was an Imperial prerogative and the one most prized by Julian.  He was unwearied in the performance of all the duties it required and he used it in his attempt to create that Catholic Pagan State Church.  The very conception is decisive proof that Julian aimed, not at the revival but at a thorough reconstruction of paganism.  He had the thought of a great independent spiritual community, wide as the Empire — a community so holy and separated that men and women who abandoned Christianity could only be admitted into it after the performance of prescribed purifying rites.  This community was to be ruled over by a priesthood set apart for the service and forming a graded hierarchy.  At the head of all was the Pontifex Maximus; next came pagan metropolitans or the high-priests of provinces; under them were high-priests who had rule over the temples and priests within the districts assigned to them.  It is improbable that Julian had completed the hierarchical organisation of the Empire before his death, but large parts of the East had been put in order.  We have some briefs which he, as supreme pontiff, sent down to his metropolitans in which he regulated many things from the dress and morals of the clergy to the training of temple choirs — so minute was the interference of the Pontifex Maximus.  Now it is possible that one form of paganism, the Imperial cult, had been strictly organised in the West and its provincial priests may have had some jurisdiction over the ministers of other cults; Maximin Daza had attempted to do something similar in the East; but the attempt to gather every cult of polytheism into one organised communion was not merely new; it was a startling novelty.  Julian's conception of a pagan priesthood entirely devoted to the service of religion was certainly not Hellenist; nor was it Roman; it was Oriental; the cults of Egypt, of Syria and of Asia had separated priesthoods.  It was a new thing to be introduced into a universal State Church whose religion called itself Hellenism.

Julian thought a great deal about this priesthood of his and recognised its supreme importance for the reformation he dreamt of making.  As the priest, from the office he fills, ought to be an example to all men, he should be selected with care — if possible a man of good family, neither very rich, nor very poor; but the indispensable qualifications are that he loves God and his neighbour.  Love to God may be tested by observing whether the members of his family attend the temple services with regularity (Julian was very indignant when he discovered that the wives and daughters of some pagan priests were actually Christians), and love to one's neighbour by charity to the poor.  Julian further insisted that the priest must be careful about what he reads.  He is to shun all lascivious writings such as the old comedies or the contemporary erotic novels.  He is to be equally circumspect in his conduct.  He must not go to the theatre, nor to spectacles, and is not to frequent wine-shops.  He is not to consort with actors nor to admit them to his house, he is even recommended not to accept too many invitations to dinner.  On the other hand he is to see that he is master within his temple.  He is to wear within it gorgeous vestments in honour of the gods whom he serves; but outside the sanctuary, when he mingles with men, he is to wear the ordinary dress.  He is not to permit even the commander of the forces or the governor of the province to enter the temple with ostentation.  He is to know the service thoroughly and to be able to repeat all the divine hymns.  Occasionally he is to deliver addresses on philosophical subjects for the instruction of the multitude.

Julian also desired that the priests should organise schemes of charitable relief, more especially for the poor who attend the temple services.  He thought that some such widely organised scheme might help to counteract the popularity of the “Galilaeans.”  He seems also to have contemplated the institution of religious communities of men and women vowed to a life of chastity and meditation — another proof that his so-called Hellenism was based much more on Oriental religions than on those of Greece.

The Emperor in all this legislation or advice was at pains to declare that he was acting, not as Emperor, but as “Pontifex Maximus of the religion of my country.”