All 6 Uses

Puritans
in
Atlas Shrugged
(Auto-generated)

He's such a rigid Puritan.†
Chpt 1.6 *

Puritan = an English Protestant who in the 16th and 17th centuries who wanted simpler worship and strict, hard-working lives
How sure are you about that Puritan stuff, Lillian?†
Chpt 1.6
Oh, stop playing the Puritan!†
Chpt 1.6
Not a stainless-steel Puritan like you.†
Chpt 1.10
That's the immense selfishness of the Puritan.†
Chpt 1.10
Don't you hear me, you stainless Puritan?†
Chpt 3.6

Definitions:

(1) (Puritans)
English Protestants in the 16th and 17th centuries who wanted simpler, “purer” worship and emphasized hard work over pleasure

Protestants are Christian groups that broke away from the Catholic Church; in the United States, well-known Protestant churches include Baptists, Methodists, Presbyterians, and Episcopalians.
(2) (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.