The Collaborative International Dictionary
Successionist
Successionist \Suc*ces"sion*ist\, n. A person who insists on the importance of a regular succession of events, offices, etc.; especially (Eccl.), one who insists that apostolic succession alone is valid.
Wiktionary
successionist
n. 1 One who insists on the importance of a regular succession of events, offices, etc. 2 # (context religion English) One who insists that only apostolic succession is valid.