Empirically, there's little to no medical evidence promoting the metaphysical states made by ACIM. The idea that the bodily earth can be an dream produced by our combined ego lacks scientific help and runs counter to the great body of medical information accumulated through centuries of statement and experimentation. While subjective experiences of transcendence and spiritual awakening are well-documented, they cannot provide objective proof of the non-dualistic truth that ACIM describes. Additionally, the course's assertion that adjusting one's feelings may alter truth in a literal sense is reminiscent of the New Believed motion and the more new law of interest, both of which have been criticized for lacking medical validity. The placebo effect and the ability of good thinking are well-documented phenomena, but they cannot help the grand metaphysical states created by ACIM.

More over, the beginnings of ACIM raise additional questions about their credibility. Helen Schucman, the psychologist who transcribed the course, defined her experience as obtaining dictation from an inner style she discovered as Jesus. This method of channeled publishing is not special to ACIM and can be found in many a course in miracles other religious and religious texts through the duration of history. The subjective nature of these experiences causes it to be hard to examine their authenticity. Critics disagree that such texts are much more likely services and products of the unconscious mind rather than communications from the heavenly source. Schucman herself had a complex connection with the product, allegedly experiencing substantial inner conflict about its material and their sources, which adds still another layer of ambiguity to the course's claims of heavenly authorship.

Additionally, the language and style of ACIM in many cases are clever and abstract, which makes it difficult for many readers to understand and apply its teachings. The program is written in a very stylized type of British, with thick, poetic prose that may be complicated to interpret. That complexity can cause a wide range of interpretations, some of which can diverge considerably from the intended message. The ambiguity of the writing allows for subjective parts, which can result in misconceptions and misapplications of their principles. That insufficient quality can undermine the course's efficiency as a practical information for spiritual growth and self-improvement.

Moreover, the professional part of ACIM cannot be overlooked. Since its book, ACIM has spawned a profitable market of publications, workshops, seminars, and study groups. While financial achievement does not inherently negate the value of a spiritual teaching, it will raise considerations concerning the potential for exploitation. The commercialization of religious teachings can sometimes cause the prioritization of profit over real religious development, with individuals and agencies capitalizing on the course's reputation to advertise items and services. That active can deter from the sincerity and strength of the teachings, throwing uncertainty on the motives behind their dissemination.