Charles Stross has lived in Edinburgh for years and you would think by now that something like "Antipope" comes off as Protestant supremacist rather than secularist in central Scotland. One of his close friends has a similar background and she had antipope as part of her email back in the nineties when I was acquainted with her... It caused a lot of issues when she was emailing someone who was Catholic, because they thought it was some kind of Orange/loyalist account.