I'm also seeing ongoing reports of very long deity lists. This user suggests it might be the result of accepting visitor petitions, (and they're definitely playing with 47.04.)
That's just a list of gods worshipped in your fortress. Which, yes, of course includes all the visitors so can get pretty long. You don't need a temple to every god, "No specific deity" fulfils normal critter's needs just fine.
The bug is when one dwarf worships far too many gods to ever fulfil its needs. One civilization only has a few gods now, so most dwarves will be OK. But some dwarves have roots in several civs so their potentially worshipped gods expands rapidly.
Toady specifically stated in the 47.03 release thread that long lists of deities were not working as intended and planned to be fixed for 47.04. I'm just passing along that the current implementation is still frustrating to some users. If long lists of deities are now working as intended, that would be useful community knowledge. Perhaps you could just link me to your information source?
Long lists of deities
for a civilization were fixed in 47.04, yes. Tarn explains it in some detail in the recent podcast interview (devblog). Civs were generating lists of gods and kept adding them until a death god turned up resulting in huge lists. He fixed that. Each civ now has shorter lists.
Visitors aren't from your civilization. The list shows the gods worshipped by everyone in your fortress.
This was hoped to fix the "one dwarf worships 30 gods" bug. But Patrik (in the post you responded to) pointed out another problem causing one dwarf to worship many gods. Believe it's on the tracker too (but search is broken for my phone there, so can't hunt it down right now).
No specific deity is fine for most visitors. One temple per god worshipped was never meant to be a thing you had to do. One dwarf has too many gods bug causes a dwarf to scream
Worship! for most of their brief lives as they desperately try and fail to worship through their god list.
So to sum up:
The long lists of gods in a temple list are caused by:
Having a lot of visitors from several different civilizations (ignore them, they'll go away).
And
One critter worshipping 30 gods bug (multiplied across a few critters causes very long lists). Fixing this will mostly fix the long lists until your visitor numbers really stack up.