Sabbath-breaker
apostate
backslider
blasphemer
deserter
disbeliever
gentile
heathen
infidel
minimifidian
nonbeliever
nullifidian
pagan
recidivist
recreant
renegade
sacrilegist
secularist
unbeliever
abolitionist
agnostic
astronomer
believer
churchman
deist
democrat
doubter
enthusiast
fanatic
feminist
freethinker
heretic
hypocrite
libertarian
naturalist
philosopher
reformer
sceptic
skeptic
socialist
theologian
worshipper