ACIM is the Anacronym for A Course In Miracles

A Course in Miracles or ACIM began with the sudden decision of two people to join in a common goal. Their names were Helen Schucman and William Thetford. They were anything but spiritual. Their relationship with each other was difficult and often strained, and they were concerned with personal and professional acceptance and status. Their lives were hardly in accord with anything that the Course advocates.

Helen, the one who received the material, describes herself here I am a Psychologist, educator, conservative in theory and atheistic in belief, I was working in a prestigious and highly academic setting. And then something happened that triggered a chain of events I could never have predicted. The head of my department unexpectedly announced that he was tired of the angry and aggressive feelings our attitudes reflected, and concluded that, "there must be another way."
As if on cue I agreed to help him find it. Apparently this Course is the other way."

"Three startling months preceded the actual writing, during which time Bill suggested that I write down the highly symbolic dreams and descriptions of the strange images that were coming to me. Although I had grown more accustomed to the unexpected by that time, I was still very surprised when I wrote, "This is a course in miracles." That was my introduction to the Voice. It made no sound, but seemed to be giving me a kind of rapid, inner dictation which I took down in a shorthand notebook. The writing was never automatic. It could be interrupted at any time and later picked up again. It made me very uncomfortable, but it never seriously occurred to me to stop. It seemed to be a special assignment I had somehow, somewhere agreed to complete." excerpt from FACIM edited for length