What is forgiveness, and when is it necessary?

As I study A Course In Miracles, the one thing that stands out is that God created all life, and that life is in Him, not "elsewhere" - meaning that He did not create something apart from Himself. If this is so, then nothing that God created is any less perfect than Himself (how could what is perfect create anything that is not perfect?) If this is so, then what is perfect cannot do but what God Wills, since His Will is the same as the will of what He created (God's creations are an extension of Himself). And what is done according to God's Will needs no forgiveness.

In reference to a post in the "Ask the Real Jesus" website that discusses the accuracy of A Course In Miracles:

I've been thinking about this one item from the ten commandments - "Thou shalt not kill".

What is really meant by that?

Does this imply that to squash a bug is no different than to squash a human being?

If it is only referencing human beings, then we have two versions of "killing", one for bugs and for human beings.

And after all, don't we "kill" fish and fowl and animals for food?

Then "killing" isn't really what is meant by this commandment, is it?

Would it then refer to "murder"?

But what is murder? Is it only the killing of another human being?

Does that mean we don't murder fish or bugs?

If a government sends a soldier to a war with an order to kill another human being, doesn't that contradict God's commandment? Or can a government decide which kind of killing is okay and which kind isn't?