He also mentions in the rest of his post and a few others that there isn't another myth for the creation of the world, and that the Chant of Light doesn't deny the actual existence of other Gods but rather their worthiness to be worshiped as Gods.
The Dwarves don't have a religious explanation for where the world came from and neither do the Elves. The Elves say their Gods came from the world, which was always there, and the Dwarves say they spring from the Stone and don't really care if anyone made the Stone in the first place.
But I suppose the point to make here is that there only seems to be one creation myth for Thedas itself, and that myth seems to date back to before the Tevinter had an Imperium. That Myth being that the Creator of Thedas was what lived in that Golden City up there in the Fade and that he didn't really do much.
If the Tevinter still believed this, even as they worshiped and spoke with the Old Gods, and tried to invade the Golden City...
Well, that leads me to wonder what the Old Gods and the Magisters thought they were really doing with all of that.