When referring to someone that is deceased, why do we say Rest In Peace?

Question

Where did that phrase come from?

Answer 1

Rest In Peace refers to the soul, not the body.

Answer 2

Some believe that souls can get stuck "in limbo", or be stuck here on earth (ghosts) instead of "crossing over" - so we would hope of our loved ones that pass on that their souls are at rest, at peace (in heaven or wherever one believes souls go after death), and that they are no longer feeling anger, pain, or any other negative feelings they may have had when their soul was in their physical body.

It's a simple prayer to mean basically all of that.

Answer 3

Because ghosts are people who died who never found peace. They end up roaming around whereever. So when someone says "rest in peace" or "be with God" that means they don't want them to be restless after death.