MCG and Mercer are totally different schools looking for different things, MCAT doesn't matter to either, honestly, if you get an interview. It's experiences outside of the classroom, how you got to where you are, and what makes you different that matters. Both schools probably received hundreds of applications with MCAT scores much higher than yours, and accepted many people with much lower scores that yours.
Your point about your family...If you have a Georgia residency status, you can come to Mercer. There are several people here who have no connection other than going to college in Georgia and then working here for a year, even though the rest of their family is from up north. Military "brats" are here too. Sure, it helps, Mercer wants people who want to stay in Georgia...So if your whole family is here, and you didn't tell them your dream is to be a plastic surgeon in LA, there's not an issue there.
Lastly - I'd say a high majority of people currently enrolled at Mercer have no church/religious volunteer experience. Probably a good many have never even stepped through the door of a church.
My guess is your stats and application are fine to be able to get interviews at both - it shows they're interested in giving you a chance - there's just something lacking with the interview portion that's keeping you from getting over the waitlist hump. You can try contacting the deans of admission at whichever Mercer campus you wanted to attend and see if they have any pointers. It also wouldn't hurt to send an update letter or maybe a letter of intent (I don't think those work, but it can probably only help).
For those of you on the waitlist - chin up, there's hope. Two years ago (not sure about the past incoming class) there was heavy movement in Savannah, probably 10 or so who withdrew (not sure about Macon, but I'd assume similar) who were initially accepted. So the waitlist does move. And it can still move all the way up to the first day in class in August. Best of luck
