Gotta chime in as well
This little topic is beaming like a lighthouse.
Being a gamer, a recent psych grad., and a believer...
Psychology is only 100 years old.
Look at the crap astronomy, biology, and physics came up with in their first century. Every science had its infancy, the cool thing about psych is that we're alive during it.
Role playing in psych is similar to role playing games. As similar as all fruits are to one another. The main focus of role playing in pyschology is to break away temporarily from one's thought process and adopt another's. This is often used for marital counseling and other environmental stressors. Frequently the role adopted is that of another person in one's life, mimicry if you will. The goal is to walk away with understanding of another's viewpoint.
Another form of roleplaying is called "2 chair therapy." Often this is done for people who had problems with authority figures (horrible parents, etc.) People are told to sit in one chair then move to the next and roleplay according to the rules given by the therapist. Chair 1 is how they reacted to given situations and chair 2 is how they wished they reacted or want to react in the future. Chair two could also be used to lash out and vent frustrations since often people cannot do that to their authorities.
This is possibly the closest thing psychology has that is similar to RPGs. Since in RPGs you can react to things that you never would yourself.
RPGs, at least the vast majority, the focus is on adopting a non existing persona. We all know its an escape. We really don't gain any understanding and its questionable if it has any use in our daily lives. Its just fun to do. It reduces stress and gives us a creative outlet - Woohoo!
From speaking to my fellow believers (those who game and those who do not) the main problem is the escape part. Some believe that all kinds of mental escape are bad; that escape is not necessary and detracts from what is important. What it boils down to is most Christian authorities believe that your religion should be your only escape. They view drugs in the same manner.
The deities, spells, etc. is just secondary stuff really. If the people who complain about DnD are purely ignorant to the subject they'll immediately go for the gods and spells but that is 80's news. Few people really believe that DnD invokes real critters and stuff these days.
Jargon and psycho-babble omitted for your reading pleasure
-Telor