Great question, nonny!
First published in The Calling, The Canticle of Silence says:
The Old Gods will call to you,
From their ancient prisons they will sing.
Dragons with wicked eyes and wicked hearts,
On blacken’d wings does deceit take flight,
The first of My children, lost to night.
I think the reason this is considered a Dissonant Verse is that it not only implies that the first children of the Maker were in fact gods themselves (that is, that they weren’t just spirits), but that they had self-agency.
That contradicts the Chant in several ways, although of course the Chant itself is fairly inconsistent about who and what the Maker’s first children are.
First,Threnodies explicitly says that humans made up the idea of any other god but the Maker, saying:
We dreamed up false gods, great demons
Who could cross the Veil into the waking world,
Turned our devotion upon them, and forgot you.
In the same Canticle, the Chant explains that the Maker’s first children were in fact the creatively-bereft Fade Spirits:
And the Voice of the Maker shook the Fade
Saying: In My image I have wrought
My firstborn. You have been given dominion
Over all that exists. By your will
All things are done.
Yet you do nothing.
The realm I have given you
Is formless, ever-changing
After this verse, the Maker then “turned from his firstborn” — that is, it was His choice to turn from his children, rather than the other way around. It’s an important point, given that Threnodies spends a lot of time portraying spirits as bereft of free will, imagination and creativity (which makes mortals special in that they DO have these traits) — thus, if the Firstborn were to be forsaken, then it must have been an proactive choice of the Maker to do so.
But the Canticle of Silence says that the firstborn children were “lost to the night”… implying that it was the Firstborn who did the forsaking of the Maker, rather than the other way around. After all, you don’t get “lost” if you just stand still and let the guy who knows everything lead the way.
Anyway, Threnodies then completes its depiction of the Maker’s firstborn as “pretender-gods”—sealed away spirits who wanted become something more:
Those who had been cast down,
The demons who would be gods,
Began to whisper to men from their tombs within the earth.
This idea is echoed in Transfigurations, which says:
As there is but one world,
One life, one death, there is
But one god, and He is our Maker.
This contradicts the idea of the Firstborn being “Old Gods” — and not just gods but Gods, with capital letters and thus on par with the Maker—as presented in the Canticle of Silence.
Hope this answers your question! And all the quotes above are taken from the Dragon Age Wiki’s list of the Chant of Light verses.