ACIM begins by stating some of it's concepts that are most difficult to grasp and so they will remain unknown to you for quite awhile. Don't push it, don't try to squeeze the meaning from it but allow it to surprise you and to reveal itself for you instead.

The guiding rope for you to navigate this section is understanding: miracles are not some magic tricks. Behind the word a "miracle" hides mental process of shifting your perception and the tool to make it happen is forgiveness, although the way this book is looking at "for giving" is not what you may think of it right now.

In swapping "miracles" -- "forgiveness" confusion goes away. An act of genuine forgiveness is meant to be applied to every thing that blows your peace, from major accidents to seeming little things like unwashed dishes or just cold outside.

When you maintain that there must be an order of difficulty in miracles, all you mean is that there are some things you would withhold from truth. T-17.1.3

And yet mistakes, regardless of their form, can be corrected. Sin is but error in a special form the ego venerates. It would preserve all errors and make them sins. T-22-3.4

It is not easier to forgive one sin than to forgive all of them. The illusion of orders of difficulty is an obstacle the teacher of God must learn to pass by and leave behind. M-14.3

The miracle forgives; the ego damns. Neither need be defined except by this. C-2.10

Forgiveness is the key to happiness. W-121