Since its publication in 1976, course in miracles has become a modern spiritual classic. The book has gained a following among those seeking alternative spiritual guidance, as well as those who are simply disillusioned with traditional religious views. It is a core text of the "spiritual but not religious" movement that has grown over the last few decades in the West. It has also been adopted by a few accredited churches. In addition, it has attracted a broad spectrum of readers from the worlds of science and the arts.

In its teaching, A course in miracles  asserts that all the wars, crime, calamities, pain and suffering in this physical universe are illusory. This illusion is created by the human ego with its false sense of separateness and fear. The true reality is one divine entity, a seamless garment that is eternally evolving into greater glory and perfection. The Course offers a way to break free of the ego's grip and regain God's vision.

The Course's stance on the relationship between God and the appearance of evil in this physical universe is controversial, and it has drawn criticism from both Christians and those who have been attracted to the work without being a member of one of its affiliated churches. It also challenges many of the core beliefs of all monotheistic religions, including a belief that Jesus Christ is the Son of God, and that all Creation was made by him and is therefore good.

Nevertheless, the Course is a nondenominational work, and it does not claim to be the only true religion or even the best one. It is ecumenical in spirit, and it states that a universal theology is impossible, but a universal experience is not only possible but necessary. It has been described as a restatement of the core wisdom found in all major world religions, and it makes no claim to be "the only way."

Although it is sometimes classified as a self-study curriculum, course in miracles is so difficult to understand and follow that most students sooner or later join a study group or one of the few accredited churches inspired by the work. The Foundation for Inner Peace, which publishes the Course, has distributed more than a million copies, and it conducts workshops, seminars and discussion groups worldwide. In addition to the main text of the Course, there are nineteen additional books and booklets derived from its teachings. Many of these have questions and answers that help to clarify the interpretation of the Workbook lessons. These are often used as study aids by ACIM study groups. These Q & A's are free to use, along with the Daily Lesson Insights, to support your own understanding of the Course.