adherent (of)	a person who supports a particular idea or party; hołdujący
convert (to)	someone who has taken on a new set of beliefs; neofita
fanatic	(disapproving) someone with a very strong belief
radical	someone who believes there should be extreme changes
reactionary	(disapproving) someone opposed to change or new ideas
bigot	(disapproving) someone with strong, unreasonable beliefs who don't accept other arguments
an assumption	unquestioning acceptance that sth is true
to derive from	to has origins in
to eradicate	to abolish, to get rid of
postulates	basic principles; postulaty
a consciousness	an awareness
to usher in	to introduce
credible	believable
credulous	gullible, naive
to give/lend/add credence to sth	(formal) to accept that something is true
ingenuous	trusting, sincere, often in a way that seems foolish
to ascribe/attribute	to consider sth caused, created or possessed by a thing or person
a tenet	one of the pronciples on which a belief is based
to give sb the benefit of the doubt	dać komuś kredyt zaufania
to take sth with a pinch of salt	brać coś z przymrużeniem oka
I don't buy it	Nie kupuję tego (nie wierzę w to)
Pull the other one	Nabieraj kogoś innego
I wasn't born yesterday	Nie urodziłem się wczoraj (nie wierzę w to)
What do you take for?	Za kogo ty mnie masz? (nie wierzę ci)