What Apostles-Creed affirming groups claim priesthood of Melchizidek?

I was looking at the online biography (perhaps an AOL or MySpace biography) of the friend of a relative some 20 years ago. I was alarmed that my relative was associated with this person, based on some very immoral vices the person was proudly describing on their page. One point that shocked me was that this person said they were "a priest of the order of Melchizidek." It was the only religious statement on the page. Q: Do any orthodox Christian groups (perhaps defined here as affirming the Apostle's Creed) use such language to describe themselves? Or would this be some sort of cult?