ACIM Quote from Chapter 1, Section 4 - Atonement and Miracles.

Atonement undoes all errors in this respect, and thus uproots the source of fear. Whenever you experience God's reassurances as threat, it is always because you are defending misplaced or misdirected loyalty. When you project this to others you imprison them, but only to the extent to which you reinforce errors they have already made. This makes them vulnerable to the distortions of others, since their own perception of themselves is distorted. The miracle worker can only bless them, and this undoes their distortions and frees them from prison.