To me, 'faith' means things like 'confidence in what we hope for and assurance about what we do not see.'
Of course, we simply see the stars. Can we figure how precisely how far away some are? There is a way for nearer stars, using geometry!
Just geometry only. Clear, and precise --
Hold a pencil 6 or 10 inches in front of your face and see how the pencil lines up visually against farther away objects like a painting on a wall. Without letting the pencil move, move your head some back and forth to the left and right.
You'll see that pencil appear to move relative to the farther away objects.
That's "Parallax".
With the entire orbit of Earth as our very long baseline, and the precision of the Hubble space telescope, we can do parallax out to 10,000 light years on nearby stars, many thousands.
So, we are not guessing when we then figure out how bright these nearby stars are quite precisely, because we know the distance to these nearby stars quite precisely.
It's not guessing nor faith. Just observation..