I use fundamentalist to describe anyone who insists on the absolute authority of a foundational text, such as the Bible or Koran. I am not in the least interested in debating the absurd and obnoxious contention that your particular sectarian belief system is the only one that can provide a basis for morality.
Ayn Rand was a mediocre political philosopher at best, and wrote awful novels, but she had some success attracting people to libertarian ideas, for which she deserves kudos.
I do not contend that. I do contend that all morality is an appeal to authority, and religious authorities are as valid as secular ones for public discussion. Moreover, secular disputes can be as intractible and violent as religious ones. So there is no reason to exclude religion from the public square.