It's too bad we've turned this term into a social joke among the ill-informed. "Sounds like you need to get in touch with your inner child!" (...laughter...) I used to be one of the joking ill-informed. And in truth, I had no idea what the heck an "inner child" was supposed to be. So... try this on for size...
Human beings are complex... consisting of many different material & immaterial parts that frequently do not agree on a common direction or state of being. For instance, I might have an argument with someone & experience my feelings telling me that the relationship is in trouble while my thinking mind reminds me it's just a passionate moment & that we are & will continue to be good friends. It's like two people in my head going in different directions. Can you relate? Human complexities include my two spiritual natures (old self & new self), my physical body (which sometimes goes its own independent way as well), my emotional mind (limbic system), my thinking mind (neocortex), my choosing mind (prefontal lobe), my reticular mind (including fight or flight impulses), & probably other things I haven't thought of.
Our emotional minds process memories, experiences, relationships, challenges, etc. as do our cognitive or thinking minds. On that emotional level we make conclusions, form beliefs, & even embrace certain courses of action that might all be contrary to the processes, conclusions, beliefs, & courses of action our thinking minds come up with. Moreover, when we're children, our neocortex hasn't fully developed, so our emotional minds are pretty much running the show.
AHA!!! There it is! Our inner child! That part of us that still functions like a child (emotionally, irrationally, impulsively, passionately, etc.) That part of us that was dramatically shaped in it's conclusions & convictions about what we are & what our world is while we were children. Still not convinced you have one of these? Have you ever yelled or thrown or hit anything in anger? Doesn't that sound an aweful lot like a temper tantrum? Welcome to your inner child!
So... if our emotional mind is our "inner child", do we have an "inner adult"? Well, what part of our minds do we rely on most heavily for making decisions that produce civilized, adult behavior? What part allows us to finish school, get good jobs, & make other well-informed choices? Isn't it primarily our cognitive mind? Example... how many us cry or laugh hysterically or show any other emotion in class or at work other than those socially accepted pleasantries required for human interaction? The intellectual, thinking adult is allowed to roam free in public; but the emotional inner child is restricted to private & generally hidden corners.
I suppose that's the real problem. On some level, many of us don't like the thought of being "children". It sounds bad, doesn't it? I think I hid my G.I. Joe action figures in my closet until my Freshman year of high school. I didn't want to get rid of them... but what a scandal it would've been if others would've found out! We want to have our lives all together ... to be cool in every circumstance ... to be relational, but also respectable. I wonder if Jesus had any such thoughts as He wept at Lazarus' death, or expressed His anger in the temple, or played with the children who came to Him. I doubt it. And yet our culture constantly tells us to "grow up", "quit being a baby", & "act your age".
Ironically, it is because of those restrictions we put on ourselves that we have such difficulty with issues of self-esteem, self-awareness, &, consequently, general maturity. When years of abandonment or abuse while growing up form conclusions in our "inner child" (emotional self) that we are powerless or unworthy of respect or unlovable... we generally respond by working harder at educating the part of us we're most familiar with ... our "inner adult" (cognitive / thinking self). But that's not where the problem really lives, is it. Maybe freedom from such inner feelings or beliefs really does require us (our adult, thinking selves) to get in touch with our inner child (our emotional selves) & begin building a new relationship within ourselves.