ascensionist

noun
as·​cen·​sion·​ist | \ -ch(ə)nə̇st\
plural -s

Definition of ascensionist

1 : one that makes ascensions or ascents a balloon ascensionist
2 often capitalized : one of a group of 19th century Christians that prepared for the coming of Christ, the end of the world, and the ascension of the faithful specifically : millerite