ass
bigot
bitter-ender
bullethead
diehard
doctrinaire
dogmatist
dogmatizer
donkey
fanatic
hardnose
infallibilist
intransigeant
intransigent
last-ditcher
maverick
mule
opinionist
perverse fool
pighead
practical person
pragmatist
purist
realist
standpat
standpatter
stickler
nonreligious person
logical positivist
Trinitarian
absolutist
animistic
empiricist
essentialist
existentialist
full-time
illusionism
mahayanist
naturalistic
nihilist
originalist
pre-socratic
thather
tried-and-true