Hi there! I grew up in Columbia, SC and I'm moving back there in the Spring and so when I saw your post I had to respond. I'm a sister of 4, 4 of the 5 of us were homeschooled by my mother. I too, was raised in the Episcopal church. I don't have too much info. to give you, since I've not lived there for 5 years, and now that I'm a mom too, my perceptions have changed as well, I'm sure, but I just wanted to acknowledge you.
Do you have a place to live already? My favorite areas in downtown Columbia are the Shandon and Rosewood neighborhoods. West Columbia, just across the river can be quite nice as well. And when I mean nice, I think yards, shady trees, walking, kid friendly ares, close to fun amenities, potential of like minded neighbors. In Shandon, St. John's Episcopal church, where my godmother attends, I remember as having a reputation as quite liberal. (their youth even have a blog! http://stjohnscolumbiayouth.blogspot.com/)
The health food stores (both in Columbia, proper), Earth Fare on Devine St. and Rosewood Market on Rosewood Dr. are GREAT places to meet like minded folks; they also have community events and billboards where you could find out more.
I think there is a free standing birth center in West Columbia. (i am curious about this as well. My son was a never-made-it-to-the-birth-center, born at granma's house, so home is where I want any future births to happen) Try searching on google. At Lexington Medical Center, Marie Bridges is the nurse midwife who birthed my sister some 26 years ago. She just might be a good contact for other professionals in the area. On another post, a woman said to check into the Sterling Sharpe Pediatric Center.
here is a link to homeschooling in SC. Click on Richland County and then scroll down for contact info. I believe the groups my younger sisters were a part of (the SC homeschoolers weren't quite so organized when I was a girl in the late 80s) were N.I.K.E. and REACH.
Blessings and safe travels for your move! Feel free to message me w/ any future questions if any of this info feels useful! Sorry these website links don't work, my pc's acting funny.