Source : Webster's Revised Unabridged Dictionary (1913)

Ritualist \Rit"u*al*ist\, n. [CF. F. ritualiste.]
   One skilled un, or attached to, a ritual; one who advocates
   or practices ritualism.

Source : WordNet®

ritualist
     n 1: an advocate of strict observance of ritualistic forms
     2: a social anthropologist who is expert on rites and
        ceremonies