LOL His? Or mine?
In my opinion, I hope they never explain it. Not being faithful myself, I adore the notion of it in Thedas. I like that there are open questions and contradictions between the creation myths between religions. And, like L Xendria said, I think these open questions underpin much of the world state in Thedas and it would lose something if Andraste suddenly showed up in Hawke's kitchen one day to explain how, yes, she was a mage, and BTW, the Maker was a fantastic lay.
So there you go, one more annoying answer.

The maker was a fantastic lay.
At the risk of revealing more than I should, I am spiritual, but I don't personally believe in what many churches and organisations demand. What I like about the faith in Dragon Age is how they show the differences between interpretations within that particular religion -- Leliana's interpretation, Anders' interpretation, and the interpretation the Chantry encourages are very different and very real. And Leliana's and Ander's interpretations are very close to my own within my own spirituality.
What I dislike about the idea of revealing the Maker as a big bad or anything like that is that it suddenly says that, no, faith is BAD. Your religion, no matter how you personally interpret it is BAD. And there's no way around the 'rules' of the religion set down by an organisation you don't necessarily agree with in that case. The faith is bad and thus you are a bad person for having faith in a 'bad' God.
That's why I prefer the untold/mysterious version. People can interpret it as bad if they like, but at least it's not outright condemned within the lore for those who want to believe Anders' or Leliana's interpretations are the correct ones.
And let's be honest, there'd probably be a lot of pissed off people if the Maker was shown as a 'good' God. So the mysterious path is the best here, I think. And I personally don't see leaving faith as an unanswered question as a bad thing in this context. As soon as Gods are brought into the equation as physical beings suddenly plots become "well, why didn't they get off their arse and do this for me?" instead of "BRB, gotta go save the day."
There's also big difference between using religion of any kind, even if fictional in this case, to defend personal bigotries and the religion being bigoted itself.