Both Uses of

Puritans
in
All's Well That Ends Well, by Shakespeare

If men could be contented to be what they are, there were no fear in marriage; for young Charbon the puritan and old Poysam the papist, howsome'er their hearts are severed in religion, their heads are both one; they may joll horns together like any deer i' the herd.†
Scene 1.3

Puritan = an English Protestant who in the 16th and 17th centuries wanted more purity and less ritual in worship, and who stressed hard work above pleasure

—Though honesty be no puritan, yet it will do no hurt; it will wear the surplice of humility over the black gown of a big heart.†
Scene 1.3 *

Definitions:

(1) (Puritans)
English Protestants who in the 16th and 17th centuries wanted more purity and less ritual in worship, and who stressed hard work above pleasure

(a Protestant is any of the Western Christian religious denominations that broke off from the Catholic Church. In the US, the best known are Baptists, Methodists, Presbyterians, and Episcopalians.)
(2) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

As a common noun (not capitalized unless at the start of a sentence), puritan or puritanical can refer to someone who is very strict -- especially about religious principles or proper behavior.