One who totally abstains from alcoholic drinks

One word substitute is Teetotaller.

Puritan: a member of a group of English Protestants of the late 16th and 17th centuries who regarded the Reformation of the Church under Elizabeth I as incomplete and sought to simplify and regulate forms of worship.
Samaritan: a charitable or helpful person
Pedant: a person who is excessively concerned with minor details and rules or with displaying academic learning.
Teetotaller: a person who never drinks alcohol.