Emperor Julian did not realize that paganism was a decentralized, overlapping set of club-like affiliations to gods, and tried to organize it like the Church.

Judged against the historical scholarship as of 2021-11. The claim has two parts: (a) Julian (r. 361–363) tried to organise paganism along Church-like lines, with a priestly hierarchy, charity and moral standards for priests; (b) he failed to grasp that paganism was decentralised, with overlapping cult affiliations. True: mainstream historians (for example Bowersock or Athanassiadi) describe Julian's Church-modelled reform and attribute its failure, at least in part, to the decentralised, plural nature of pagan cults that he misjudged. Mostly true: (a) is well supported, and historians accept the decentralisation point but frame it as a structural obstacle rather than a failure of Julian's understanding. Mixed: (a) is supported, but scholars largely reject the idea that Julian misunderstood paganism, for example because they argue he knowingly tried to reshape it. Mostly false: the reform programme is overstated and the 'did not realize' framing is contradicted. False: historians reject that Julian tried to organise paganism on a Church model at all.

Set before the research began.

1. E1 The ‘Pagan Churches’ of Maximinus Daia and Julian the Apostate | The Journal of Ecclesiastical History | Cambridge Core Cambridge University Press (Journal of Ecclesiastical History) · 6 February 2009

   “Arsacius was invited to consider and attempt to imitate the practices which had made Christianity so successful, in particular Christian hospitality towards strangers, reverence for the dead and the pretended piety of Christian lives. Pagans too should practise works of charity.”

2. E2 julian the apostate's religious policy and renovatio imperii ... Classica Cracoviensia (Jagiellonian University, Kraków), by Anna Mleczek · 2020

   “the radical reinstatement of the pagan cult, given such religious conditions, was impossible (regardless of the methods and means adopted) due to the lack of a proper social basis and acceptance; moreover, it met with the reluctance of Christians and the indifference or reserve of pagans”

3. E3 Introduction: Approaching Julian Brill (A Companion to Julian the Apostate, ed. Stefan Rebenich and Hans-Ulrich Wiemer) · 8 January 2020

   “The second question concerns the extremely heterogeneous set of religious practices and discourses that Christian clerics stigmatized as pagan:”

4. E4 [PDF] JULIAN'S APOSTATES: CONVERSION TO PAGANISM IN THE MIDDLE OF THE FOURTH CENTURY Schole: A Journal for the Study of Graeco-Roman Antiquity (by M.A. Vedeshkin, Russian Academy of Sciences) · 2023

   “It is concluded that Julian’s efforts at returning the Roman Empire to paganism were far more successful than it has traditionally been thought.”

Part (a) is supported. A 2009 Journal of Ecclesiastical History article titled "The 'Pagan Churches' of Maximinus Daia and Julian the Apostate" (E1) describes Julian urging the priest Arsacius to copy Christian practices, including charity, hospitality and pious lives. For part (b), a 2020 scholarly companion (E3) calls the practices labelled pagan "extremely heterogeneous", and a 2020 article (E2) says restoring the cult was impossible because it lacked a social basis and met pagan indifference. These sources treat the obstacle as structural and do not say Julian misjudged paganism's nature, which matches the "mostly true" criterion; E4 dates from 2023, after the judging date, and was not relied on.