That was what his Christian enemies accused him of - in fact, what he attempted to introduce
was a sophisticated monotheism rooted in the Neoplatonism of Plotinus -
a very different matter from the old Roman gods. That article is amusing,
but I think it exaggerates that 'eccentricity' of Julian's beliefs,
as they are expressed in his surviving writings as opposed to the propaganda of his enemies,
and it uses 'paganism' as a catch-all term for any beliefs and religious pracitces
other than Christian or Jewish.
Eul, didn't you get the memo? We no longer live in rational, evidence based times.
On a separate note, I found this little pic interesting, the contrast between (recruitment) propaganda and reality