Well - Performing marriages without a valid marriage license is illegal in North Carolina.
"No minister, officer, or any other person authorized to solemnize a marriage under the laws of this State shall perform a ceremony of marriage between a man and woman, or shall declare them to be husband and wife, until there is delivered to that person a license for the marriage of the said persons, signed by the register of deeds of the county in which the marriage license was issued or by a lawful deputy or assistant."http://www.ncga.state.nc.us/EnactedLegislation/Statutes/PDF/ByChapter/Chapter_51.pdf
Understood.But I'm addressing "marriage" as it would be described by a religious denomination.The Episcopalians (for example) are free,and should be free,to declare any two (or more) creatures to be "married" in the eyes of their "God".But to perform a "marriage" that's recognized by the government,for the purposes of filing a joint tax return (for example) certain requirements must be met...as you've noted.