By 
Your belief in a wrong mind thought of the unreal ego is what you are learning to forgive in A Course in Miracles (ACIM). Belief is intangible, since it is nothing more than an agreement or an investment of the mind in a particular idea or thought. You use choice to invest faith in the thoughts of the ego that harvest the power of the mind in the wrong creation of this world. It is your faith in these ideas that needs forgiveness and that makes forgiveness seem difficult. Decision making in the mind is what you use all the time to believe or disbelieve any thought at any given moment. This power of choice is where you have all the power to choose between heaven and hell.
There are two famous phrases in the Course about how to make the unreal appear real and about ideas that do not leave their source. Choice and faith are directly involved in both. Here are three (3) key word symbol definitions that we will consider to promote discussion:
Thought: an idea or opinion that occurs in the mind.
Choice: The ability, act, or possibility of making a selection between two or more ideas.
Belief: Accept an idea as true or real.
If we look at these definitions in order, it is clear why the Course is aimed at the decision-making (choice) capacity in the mind that can observe thoughts (ideas) and decide to believe or not believe in them. It is the capacity of observation where the choice is made to believe in the unreal or to withdraw the belief in it (forgive) and thus correct the mind.
Making it real
Course students frequently misunderstand what it means to do something real and how choice and faith are what does that in the mind. Having an unreal ego thought and choosing to believe it is what makes it seem real. Invert the mind and therefore the idea remains with you, as you have taken it seriously. Belief is the judgment that you agree with the unreal idea about reality.
Consider it another way. First, you just have to take the trouble to choose to believe in something, that is, make the unreal appear real, if it is “unreal” since the unreal does not exist. If you laughed and left him alone, what doesn’t exist is still non-existent. Second, it will only go to such trouble to prove that your unrealistic idea is correct, and therefore why the Course states that it all comes down to whether you want to be right or happy.
Choosing to believe in an unreal idea is the option to prove that your idea is correct, so that it seems real and forgiveness (withdrawing the belief) seems difficult because you have invested a lot of effort in its wrong creation and in being right. That brings us to the next topic where ideas don’t leave you as a source.
Ideas don’t let you
By itself, an ego thought is nothing (unreal) and will remain unreal despite your choice to believe in the idea. It is the misperception of the results, or the effects of believing in the unreal come true, that keeps the idea with you because you are still investing the belief in the idea. You are adding more faith as you still take it seriously. The idea never left you because you never left it (you forgave). The next logical step has to be to deny the Truth.
In a mind divided between the unreal and the real, the ego and God, what the Course says is that from the first unreal idea of separation and all subsequent options of mistakenly believing in unreal thoughts as solutions, you have fragmented yourself. the mind. Forgiveness seems difficult because you are so committed to being right and so scared by what you have done.
The Course is also trying to tell you to start denying the ego’s unreal lies and stop denying the Truth. Do the opposite of what you are doing now. Look at where you are choosing to invert your beliefs in the mind so that you can learn to forgive (correct your mind), which is to withdraw the belief in the unreal. The fear of God is also an unreal idea that you believe in. In fact, you have not “done” anything, since the unreal does not exist.
Believe means denial, repression and projection
These are the ego’s key defenses due to the guilt behind the decision to believe in the unreal. Without going into the explanations of the Course, we are all aware of guilt and have chosen to continue with the ego’s unreal ideas about what to do with guilt. No one in this world is exempt. You can pretend otherwise, but that is denial and repression and belief in the ego. They lead directly to the projection.
Let’s look at the definitions of the word symbols:
Deny: Refusing to admit the truth.
Denial: A statement or declaration of something as false.
Repression: Suppression of a thought or feeling.
Projection: a mental image seen as reality.
You cannot deny and repress unless you first go to the trouble of making the unreal real and stick with the idea. The guilt behind those choices upsets you. Not only has he refused to admit the Truth, he has also denied what he has chosen. That’s twice the guilt that bothers you, and if repressing doesn’t work, you’ll project it “out there” into a world and bodies mistakenly perceived as “reality.”
The projection does not hide the guilt. It leads to guilt and attack to promote the belief in guilt, which is also an unreal (old) idea that the mind chose to reverse the belief in. Again, faith is judgment. The ego only survives through judgment. Forgiveness is withdrawing faith in what is not real.
Not believing is forgiving
Consider the immense power this mind-making ability has if you just stop and go back to your mind and observe what you are choosing to believe or not believe. You have forgotten that choice by mistakenly believing in the unreal, what does not exist, is all that is happening. What exists is real. The peace of God is in forgiving or withdrawing faith in the unreal and returning the mind to the real.
It is only by observing that you will learn what the cost of continuing to choose to believe in the unreal world of projections, as well as continuing to suppress and deny guilt, really requires. Likewise, it is only by observing that you can learn to recognize those beliefs and how to renounce them (forgive). You have to face what is really costing you to be right. This is a world of ever-changing misery, pain and suffering, full of guilt and attack, and where momentary happiness is considered better than eternal happiness.
When that cost is not worth it, you will take the time to learn how to give up your beliefs in your wrong decisions about where to invest your mind. Heaven merely waits for this recognition and willingness to unlearn what you have taught yourself and for a different inner Teacher to teach you how to choose again (forgive, correct your mind). Eternal happiness is choosing the constant and real (Truth). It is immutable and therefore totally reliable because it is complete.
To choose the Truth once again is to seek and observe in your mind these beliefs in the unreal and then choose to renounce them (forgive). Just as the world is not real, neither are beliefs. The investment choice makes the belief seem real in the mind.
The light of “separation never occurred” (the Atonement) shines for your choice by choice, slowly but surely illuminating the way home as you withdraw faith (forgive). Forgiveness is part of the solution, the Principle of Atonement which is an act of Love from the Father in response to His Beloved Son having a foolish and unreal idea of separation, choosing to believe it, and also choosing to keep it with him.
Beyond this world is the magnificence of our True Self, where Love extends throughout eternity in a Song of Prayer between the Father and the Son, Creator and Created as One. If the foundation of the ego is separation , then the foundation of salvation is equality. This world as proof that the idea of separation is still with us means that we must all observe and forgive our minds to return to equality within our unreal ideas that have not abandoned their only source. Each of us is a fragment of the One and the decision-making mind is where we all have a choice to believe or not to believe.