Wow. Lots of comments. Most very interesting and reasonable.
I titled this post a ‘rant’, and stuck it in the non-BSG thread area deliberately. I didn’t expect much response…
I was still… angry is not the right word… dissatisfied… empty… upset… yes, that’s it… with the denouement.
I did not have a problem with religion in BSG for 4.19 seasons. It was wonderfully ambiguous; much like our ‘real’ world. The so-called ‘mystical’ events could be explained away, either rationally, or as dramatic licence. The ‘heads’ to me remained internal psychological manifestations: their knowledge of the world, their real influence was minimal (as OT has argued strongly), the apparent physical manifestations ambiguous.
Prophesy was as prophesy is. Gibberish which can be taken any way one likes - especially in hindsight.
There were some events (especially the supernova) which hinted at more, but dedicated a-theistic types like me could dismiss them.
But all this was blown away at the end. The carefully layered subtlety, the hints, the coincidences, the concept of leaving interpretations of the mystical to the individual, this was destroyed by the clumsy final reveal.
The years of generally pretty-good science were crushed with the ill-conceived, and clearly impossible (from an evolutionary viewpoint) arrival on earth in our recent past, and discovering other genetically-similar-enough humans.
You see, it wasn’t the god-or-no-god which got me: it was the massive inconsistency with what had gone before.
There could easily have been reveals to satisfy both the most rabid theists and the mystics, as well as the grouches like me. Simply arriving on earth 8000 years into our future would have left the main science intact. And not had any deleterious impact on the existence of god, heads, etc. By firstly having the Head Six and Head Baltar stand next to, but not acknowledge each other, and then later not interact together, the mystery about what they were would have still remained. Strong arguments for internal as well as external agents, real or imaginary, could still have been made.
Why was the end so UNSUBTLE? BSG, for years eschewing so many traditional American TV norms and tropes, suddenly caves at the end with explicit and overt explanations when it has never done so before? Moore reverting to STTNG form?
So… it was in this context I wrote my rant here - jumping on an (obviously) favourite hobby horse of mine as a vehicle of my dissatisfaction. Hopefully you may note my posts in other threads to be slightly less strident… 
PS
Again, thanks folks for all the fascinating comments. GWC has always been so tolerant and polite - even in heated arguments - far better than any other forum in which I have participated. MissM, Cas, OT, HotChicken, and many others have crossed swords with me over the months, and we have all maintained wonderful respect for each other, and a lack of rancour or personal abuse. Well, apart from that godless Sandstorm idiot…