Is there some reason you want to live in Henderson? I would recommend Durham, 30 minutes or so down I-85, over Henderson if you're looking for other liberal, unschooling, non-religious, vegetarians to hob-nob with. I really don't know that much about Henderson, but have visited a few times since my DH has relatives there.
The thing about NC is we're a really patchwork purple state in the sense of having some really liberal blue areas and some really conservative red areas. Henderson is going to be more of a red area and Durham is much more blue. The urban areas of NC and the college towns are, as you might guess, going to be more blue. Henderson is a small, more typically Southern, manufacturing city surrounded by rural areas, so it's going to have a conservative base. I think DH's relatives are pretty typical of Hendersonites — good church going folks who I'm guessing tend toward the conservative in politics, though I've never spoken of it with them. Since our state is growing so rapidly and so many folks are moving in from elsewhere you might find a few like-minded souls who have also moved there, but my best guess is you're not going to find a whole lot of homegrown, vegetarian, unschooling, non-religious liberals there. I wouldn't discount that there may be some, though.
There are tons of folks who meet your description in Durham, Chapel Hill and Carrboro and also quite a few in Raleigh. Other smaller towns to consider include, in the western part of the triangle, Hillsborough, Pittsboro, Mebane, Efland, and Saxapahaw.
ETA: Found this scathing thread on city-data
that you might find more informative. I think I wasn't thinking about how high the African American population is when I said that the town was conservative, so my reading of that may have been off, but I think that you would find that most whites there are very conservative. So if you're looking for the "educated progressive", maybe not so much in Henderson.
ETAA: This little rundown
is less scathing than that city-data thread, but if you look at the numbers it might give you pause about moving there. Sounds fairly economically depressed.
Btw, I googled +"Henderson, NC" +liberal and got those links on the first page. I'm sure if you googled other areas and attributes ("Durham, NC" and "vegetarian") similarly you could find other interesting results.