Verified answer

Clifford was actually not a big red dog at all.

He was simply a figment of Emily's imagination, as she suffered from intense schizophrenia. However, unlike all of the other entities that she imagined, he realized that he didn't exist and tried to get Emily to believe he didn't in order to help her(which is all of course just Emily's mind trying to help herself).

She said that he was there because she believed it, but Clifford would constantly explain to her that was an unethical way of thinking because it caused her to ignore the real world around her.

She worshiped Clifford like a God, which Clifford did not like one bit, while her friends and family around her mourned the loss of her sanity. He was anti-theistic because he was like a deity, wishing to end his own existence.

I believe that the pictures in my television set are sent over the air waves, invisibly, in a constant stream of data.

However, lacking the knowledge of exactly how this can be doesn't stop me from believing in it.

I feel so unethical.