I am 110% behind this. I know it's what I argue for all the time on this forum and I get that not everyone is going to agree with me here,
but the humanization of deity is a central theme to DA:I. The more you believe in your own mysticism and godhood, the more out of touch with reality and power hungry you become. The more power you obtain? The more proof that God/ the Maker is behind you. It's a self-fulfilling prophecy bound in nothing but pride and obsession. It will result in nothing but terror and disaster. Andruil and Falon'Din are the most fitting examples of self-delusion and lust for power.
The more detached and critical you are, the more you are capable of seeing the truth. That others contribute to your success, that your power isn't your's alone. If anything, you could see yourself more as a pawn used by others for position and status. Or even bait - you become the focus, drawing it away from the true players of the game (here's looking at YOU, Solas). You are nothing but a distraction to the aeons long war you've stumbled upon by nothing but chance. Who knows, maybe even the elven gods were nothing but chess pieces in a much larger game we have yet to see or realize.
Yeah, that is what I thought too. Even Solas says so.
The "gods" sound like powerful mages who created their own godhood. Like Corypheus. He symbolizes this arrogance.
If somebody claims to be a god you can be pretty certain they are not. If somebody claims to speak for god, just as bad. Run for the hills! *g* It's probably the oldest excuse in the world for tyranny. "God told me to do this."
Interesting that Solas seems to make no such claims. But maybe he *is* Satan then after all. What was that again? "The greatest trick of the devil is to convince you that he doesn't exist." 
However, there is always a ton of spirituality in Bioware games. They take all the wisdom from various religions and retell mankind's oldest tale in their games. What is human nature and what is god? So yes, you can compare characters like Solas to various religious and mythological concepts like Satan or any archetype in literature. Bioware knows them all. Most stories can be broken down into the same few elements. If I had a better memory and deeper knowledge on literary tropes, I could give a more detailed reference. But I'm sure most of you know what I mean.
Given his role in the reincarnation cycle of elves, there's no doubt in my mind Solas knows who and what Sandal is, and Sera as well. His prodding throughout the game isn't pointlessly needling her: he's trying to probe to determine exactly how much Andruil is still left in there- whether she can reconnect to a larger part of what she once was.
So, how does this work then exactly? How does an OGS interact with their host? What makes the difference between somebody like Solas or Flemeth who are fully aware gods who just wear the face of a mortal and Sera on the other hand who's OGS is asleep? Apparently body hopping does not automatically make them assume complete control then. So what needs to happen? Does it depends on how big a part of the OGS is put into somebody? I struggle with understanding this if your theory is true. And would Sandal be like Sera, unaware? Or fully aware and the dumb boy stuff is just a mask?
How many of the gods are still even sealed away then? Or are only aspects of them walking Thedas? And to gain their powers in full they need to merge all part of their souls together again? But part of all the gods are still locked? Sorry if you elaborated on all that already, I'm still catching up...