"Most millenarian" refers to something or someone that is extremely preoccupied with the idea of the apocalypse or the end of the world. Here are some synonyms for the phrase: doomsday enthusiast, apocalyptic fanatic, eschatological zealot, end times enthusiast, armageddon aficionado, last days fanatic, judgment day devotee, cataclysmic true believer, and end of the world adherent. While these terms may have different connotations, they all describe a person or belief system that is focused on the idea of an impending, catastrophic event. It's important to note that while some people may view these ideas as extreme or paranoid, for others they may be a source of comfort or motivation to live their lives to the fullest.