In the White-Stafford debate, QEOS is pronounced as thay-ahs. Interesting point on W. In English, hO WN might be uttered as "ho ahn", and this might work for casual, non-scholastic conversation. But, how is the omicron pronounced here? For ANTILUTRON, I've been uttering antee-lootron (without rolling the r, but I've gotten better at that). The rho was rolled too, right?
My [edited] answer:
I would not say that thay-ahs is wrong: it is maybe one way to pronounce the Greek morpheme θεός; but epsilon is short, so that is one reason why I do not pronounce θε as "thay." Biblehub.com has "theh'-os" for the Greek θεός.
Όμικρον (ο) has an interesting phonological history. At one time, it was enunciated differently than Ωμέγα. Donald Mastronarde describes Ωμέγα (ω) as "a long open central-back vowel" which was pronounced like the English "saw." On the other hand, Όμικρον is "a short back mid vowel," vocalized like the 'o' in the German "Gott." But, historically, there evidently came a time when ω was no longer phonemically distinguishable from ο in Greek: that is why the Byzantines made a morphemic/graphemic distinction between Ωμέγα and Όμικρον. And, if you will notice today, some say λόγος with a short 'o" and others treat Όμικρον in the word as a long vowel. Again, either way is acceptable except to the most persnickety purist.
For what it is worth, I purchased a copy of Randall Buth's proto-CD for "Emic Koine." Buth says that ω = ο in Modern Greek--ο is lower than ω in the Erasmian system and in the Allen-Daitz "restored Attic" system, ω is longer and lower than ο. The page found here is also quite helpful:
Lastly, the ϱ (r) was likely trilled, but I haven't traced its history to see if that practice stopped at some point.