Now that Mr Trump has proclaimed the final defeat of ISIS, this may at last be a safe moment to reveal that I am, myself, the Founder of Isis*.
It happened in a modestly Anglo-Catholic establishment on the South Downs, called Lancing College. In 1973, newly appointed, I founded a Society which gave members the opportunity to get off the campus and attend meetings in my house and to go on expeditions which did not exclude hostelries (nowadays, organising such society activities would be an instantly sackable offence). Quite why we chose Isis as our Patron, I cannot now remember; but we had nice ties manufactured bearing the hieroglyph of Her of the Throne. I still have one somewhere. You had better not tell the CIA.
In the first centuries of the Christian era, Isiacism was a very attractive syncretistic religion. It denied the validity of no other religion; it conceded that the same Deity was behind all the divine names in all the cults. Isis was the preferred name (and her mysteria the most satisfying); but in no exclusive way. Like PF, they believed that plurality of religions was part of the Divine Will. I have often wondered why those relativistic Christians who take an analogously syncretistic stand because all religion is at root the same, do not have courage of their convictions and rebrand themselves as Isiacs. It would be a particularly attractive cult for those of them who, by an unfortunate accident, have like poor dear Apuleius got themselves metamorphosed into donkeys with oversized membra virilia.
Moreover, if only the Right Side had been victorious at Actium, Isis might have had a great literary future. After all, Cleopatra VII, the philopateira Thea, was also the Nea Isis. Would Vergil, instead of writing that rather tortured aetiological epic about the Ira Iunonis, Venus Genetrix, Pallas puer, and Pius Aeneas, have poured all his heart and genius into an Isiad, which would have climaxed, not in the vengeful killing of Turnus paidophonos, but in the divinely glorious Nuptials and exquisite couplings of Isis Epiphanes with her Neos Bakkhos? Er ... perhaps not ... I admit that you are right. He probably wouldn't. No scope there for his libido pronior in pueros. But somebody else might have done it. Publius Ovidius Nosey, for example.
Since an excitingly Hellenistic Romano-Alexandrian Empire would have had a much more Eastwards bias than the boring old Roman Empire did, the Name of Isis would have been Great in the Orient, two thousand years earlier than today.
*To make Isiacs feel at home in Oxford, we have renamed our bit of the Thames after the Goddess, and divided our other river, the Cherwell, into two parallel streams so that we can call the bit in between them Mesopotamia.