I'm really surprised certain parts of the fandom haven't ripped Cassandra into pieces over the "How could the elves pour such devotion into this nonsense?" at the Temple of Mythal.
She's pious, but is pretty open-minded. She might not agree with an Inquisitor who doesn't believe in the Maker but it doesn't prevent her from getting along with them.
The Elven Pantheon might not have been gods,
but its suggested that they drew power from worship. The Fade reflects the thoughts and dreams of our world, and the Avvar have shown that spirits can gain godlike power through ritual and worship. If the Pantheon bound spirits to objects like the Orb they would have tremendous power.
My crazy tin-foil hat idea is that the Maker
doesn't exist, not yet at least. What Andraste saw was just a spark, to bring something with the power to shape entire worlds into being takes a lot of power, which is why the Chant promotes spreading the faith across the entire world. The whole "the Maker left us and we have to redeem ourselves" justifies why he doesn't intervene.