perfectionist (n.)

1650s, from perfection + -ist. Originally theological, "one who believes moral perfection may be attained in earthly existence, one who believes a sinless life is obtainable." The belief has prevailed from time to time in some Catholic communities, Arminian Methodists, the Society of Friends, etc. The sense of "one satisfied only with the highest standards" is from 1934. Related: Perfectionism.