His most notable work was the Oracles of Agathagelos (Οι χρησμοί του Αγαθάγγελου), a forgery presented as the prophecies of a 13th-century monk.

It had a huge appeal in the court of Catherine II in Saint Petersburg and greatly enhanced philhellenism in the European cities Polyeidis personally visited.

He wrote the Oracles of Agathangelos (el),[4][usurped] a well-known prophetic work which was published, with minor variations, widely in Greece, either as a brochure (by Rigas Feraios) or as a book in Athens and Ermoupoli (1837–38).

He dates the oracles back to the 13th century (1279), and claims that the original author of the work is the monk Ieronymus Agathagelus from Messina in Sicily.

He stayed in Dresden (1741) and shortly afterwards settled, after an invitation of the inhabitants, in neighboring Leipzig, where he founded the first Orthodox chapel (then of the Holy Trinity, now of St. George).