I thought I should mention a very important part of Sam's revelations from 4x15, which passed so quickly that I actually missed this on my first viewing.
GALEN TYROL: "So, we knew the end was coming"
SAM ANDERS: "We'd been warned, yeah"
(later that day)
SAM ANDERS: "Back on Earth, the warning signs that we got, it looked different to each one of us - I saw a woman, Tori you saw a man... funny, no one, no one else could see them... Galen, you thought [unclear - possibly "you had a ship in your dream"] ... Saul stay with the fleet, it's all starting to happen, it's the miracle, right here, it's a gift from the angels"
This adds an entire new element, and points to a potential plot closure.
Baltar, we know, has been having visions of a Six from the very beginning.
Caprica Six, on at least one occasion, had visions of a Baltar.
And Kara had the dream/vision of visiting her mother, guided by a Leoben... who told her he wasn't Leoben.
AND Saul kept seeing Six as Ellen.
Men see women, women see men. Who do they see? Angels?
A few possibilities:
1. The gods (Zeus and the pantheon), from Kobol, are real.
2. The One True God
3. (Either 1 or 2 or someone else turns out to be) the creators of the "humans" on Kobol (i.e. all this has happened before...)
4. Some very advanced/enlighted people who survived the war on Kobol.
5. The Ship of Lights people (this would be pretty far out there)
Whomever they are, they have been sending visions for at least 2000 years, and it's possible they are the ones who resurrected Kara (although I think a more straightforward theory is more likely for Kara's resurrection).
As described in the Battlestar Wiki (from the original series):
The Beings of Light are a mysterious race that travel using the Ship of Lights. Called angels by the primitive people on Kobol, these creatures helped them develop the civilization that would become the Twelve Colonies (War of the Gods).
I've speculated on this before:
In case you're finding all the Galactica mysticism weird, be aware it's not new - I suggest you locate the only watchable episode of Galactica 1980,
"The Return of Starbuck"
As it happens, it was just on Space yesterday as well.
In it, Starbuck crashes alone on a desolate planet, and wonders whether he may have died and is in the afterlife. He finds a crashed Cylon ship and, bored with a lack of companionship, rebuilds a Cylon ("Cy") and befriends him (after he convinces the Cylon not to kill him). Eventually, the Cylon feels that Starbuck is bored with him, so the Cylon goes to find a wo-man for Starbuck. Rather surprisingly, he returns with a pregnant one. Cy says something like "I'm sorry if you don't like this one, there wasn't much selection". When Starbuck asks the woman where she comes from and how she got on the planet, she replies, "from another dimension, in the usual way". As a bonus, she informs Starbuck that she is carrying their "spiritual child". She also informs him that they must build a ship, because the Cylons are coming, and will bring Judgment Day with their arrival.
The child ends up being the incredibly annoying Galactica 1980 Dr. Zee, which is why I refer to New Galactica's hybrid baby Hera also as Dr. Zee.
from my posting "bg 3.04" - Sunday, October 22, 2006
The canonical set of classic Galactica glowy god-being episodes is
Galactica 1978 - 15 & 16 - War of the Gods
Galactica 1980 - 1x10 - The Return of Starbuck (the final episode of the old series)
Interesting geek sidebar: Buck Rogers also had glowy time lord guardians of forever people and a box full of Time.
BSG 4x1 - Sunday, April 06, 2008
(I can't believe they've been making us wait since last April to wrap this up.)
I've discussed the specific scenario of the visions coming from the gods before, S3 or S4:
S1. Most likely: In the nuclear explosion that killed Caprica Six as she was holding Baltar, her upload got mixed in and crossed over with his brainwaves
S2. Baltar vision Six is an implant or some other technology used by the Kobol-Earth Cylons to guide Baltar, as part of their Plan (putting him roughly in the same class as Kara and Galen)
S3. Angel sent by God / Demon sent by Forces of Evil
S4. I think fairly unlikely: Angel / vision sent by Glowing Ship Gods (see original Battlestar)
(If it does end up being some Ship of Light literal deus ex machina I will be disappointed.)
the Cylords of Kobol - December 23, 2008
And all of this ultimately comes back to the questions I posted in who is the puppet master? (April 28, 2008)
It's clear that on one level, Cavil is the puppet master.
But whose puppet is he? Is he doing the work of the devil, or of angels?
One of the scenarios I suggested
Lords of Kobol / glowing god ship people
We also still have the Hybrid's prophecy to consider, most of it has come to pass except
A dying leader will know the truth of the Opera House.
Galactica 4x06 - Tuesday, June 03, 2008
(Unless "the Opera House is a pile of rubble" is the truth, but that's certainly not what was implied by the visions that Roslyn was having.)