-ist

(Greek > Latin: a suffix; one who believes in; one who is engaged in; someone who does something)

parochialist
parthenolatrist
Someone who worships a virgin, or virgins; referring especially to the Virgin Mary.
particularist
paternalist
pathologist (s) (noun), pathologists (pl)
A medical doctor who specializes in identifying diseases by studying cells and tissues under a microscope: A pathologist is an expert who strives to determine the essential nature of diseases, especially of the changes in body tissues and organs that cause or are caused by diseases.
patrist, patristic
One versed in the lives or writings of the Fathers of the Christian Church.
pedagogist
A teacher of children.
pedobaptist (s) (noun), pedobaptists (pl)
A person who practices, adheres to, or advocates infant baptism.
pedodontist, pediadontist (s) (noun); pedodontists, pediadontists (pl)
A dentist who practices dentistry that deals with children's teeth.
pedologist, paidologist (s) (noun); pedologists, paidologists (pl)
A person who studies children and their behavior.
pedorthist
A person skilled in pedorthics and practicing its application in individual cases.
pedotrophist (s) (noun) ,pedotrophists (pl)
A person who is skilled or has the knowledge, the ability, or the training to bring up children properly.
pegologist
pegotherapist
pejorist (PEJ or rist)
Someone who believes that the conditions in the world are becoming worse; such as, with climatic changes; what is happening with economics and government policies; religious hypocrisy or pretense of virtue; internet fraud; military wars; terrorism in the name of religion; greed, public and private individuals; false accusations in politics; ego-centric, foul-mouthed, rabble-rousing (stirring up the passions or prejudices of the public) talk-show hosts (on radio, television, and at rallies) and their followers; company executives, politicians, and others who lie and commit fraudulent acts; etc., etc.