I wish there was one that I could share with you that isn’t segmented into parts. This may work for some of you:
Share Holst: Cloud Messenger; Hymn Of Jesus; Ave Maria; Evening Watch; 7 Part-songs; Choral Fantasia; Other Works by Gustav Holst
I think it is helpful, in thinking about Gnosticism, for students to try to imagine Gnostic worship. The singing, prayer, and other devotional practices of a religious community are at the heart of its meaning to believers, and not just (or even primarily) the study of texts. I’m not suggesting that Holst’s setting sounds anything like what ancient Gnostics actually sang, of course. But listening to anything – even a modern setting – can still be a useful undertaking.
There are other settings of extracanonical texts that are worth being aware of. Joaquin Rodrigo (famous for his Concierto de Aranjuez) set some Qumran hymns, and Alan Hovhaness set some of the Odes of Solomon.
There are also some Mandaean hymns recorded on YouTube, but I have yet to listen very carefully to try to figure out what the texts are.
Any other recommendations for extracanonical, heretical, and/or Gnostic music?