Quote from A Course in Miracles Text Chapter 2 - THE SEPARATION AND THE ATONEMENT.

T-2.VI.5. Fear is always a sign of strain, arising whenever what you want conflicts with what you do. 2 This situation arises in two ways: First, you can choose to do conflicting things, either simultaneously or successively. 3 This produces conflicted behavior, which is intolerable to you because the part of the mind that wants to do something else is outraged. 4 Second, you can behave as you think you should, but without entirely wanting to do so. 5 This produces consistent behavior, but entails great strain. 6 In both cases, the mind and the behavior are out of accord, resulting in a situation in which you are doing what you do not wholly want to do. 7 This arouses a sense of coercion that usually produces rage, and projection is likely to follow. 8 Whenever there is fear, it is because you have not made up your mind. 9 Your mind is therefore split, and your behavior inevitably becomes erratic. 10 Correcting at the behavioral level can shift the error from the first to the second type, but will not obliterate the fear.