This 1980 film also goes by the name of Cataclysm and Satan's Supper.
Claire Hansen (played by Faith Clift, star of Night Train to Terror and Horror Express) is having strange dreams involving Nazis, much to the chagrin of her husband James (played by Richard Moll, Bull of Night Court -- with hair no less, or a lousy toupée). Meanwhile, an aged concentration camp survivor has seen a Nazi from the camps, only the Nazi hasn't aged and still looks 25. He tries to convince his policeman friend (played by long-time tv-actor Cameron Mitchell) that it's the same guy, but to no avail. He is killed confronting his tormentor from the past.
Meanwhile James, (who writes books denying the existence of God), is visited by a man named Papini who is branded with the mark of the devil (666) but warns James that the devil is returning.
Somehow everyone shows up at the same disco, where it turns out that the apparently unaging Nazi is the devil. Or at least one of the devil's flunkies.
This is a really low budget film; the acting is mostly of the amateur hour variety, and there is nothing special about the effects. However, the story is entertaining and it's filmed with just enough professionalism to be watchable, provided nothing else is on.
It just goes to show you that the menace of the Nazis never ends, just like this movie.