If I was describing my long dead Grandfather Hartley to someone, even though he has passed away, I shouldn’t just make up anything I feel saying about what he looked like in order to describe his physical features. For instance, if I say “he was a giant of a man, a physical paragon, with blond hair and piercing blue eyes, except for his whiny and scratchy voice”, I am simply not telling the truth. That is not what my Grandfather looked like at all.
My grandfather died when I was young, and I only recall a single sentence he said, which, to my memory, was in a voice that was neither strikingly bass nor tenor, but similar in tone to a much deeper version of my mother’s voice. As a child I got up onto his lap and my parents saw it, and thought I was behaving too wildly for that, and told me to get down because I would hurt him. My grandfather, who was smiling and happy, said something to the effective of “Oh, let him stay” or “Oh, let him stay on my lap” to which my parents agreed. He welcomed me back onto his lap with a broad smile.
As my grandfather was a real, living person, it matters what I say about him.
If the atonement was not a real thing, then it wouldn’t matter what doctrines we taught about it. We could say anything we wanted about it. However, because the atonement is real, it matters what doctrine we teach about it.
There is a dramatic difference between today’s popularized authors on the atonement, and the actual doctrine of the atonement. Since the atonement is real, two directly contradictory ideas about it cannot both be true. It is a real thing. It matters what we teach about it.