religious vs irreligious

religious is a noun but irreligious is not a noun.

Word	Noun	Adjective	Verb	Adverb
religious	Yes	Yes	No	No
irreligious	No	Yes	No	No

religious (noun)	irreligious (noun)
a member of a religious order who is bound by vows of poverty and chastity and obedience

religious (adjective)	irreligious (adjective)
having or showing belief in and reverence for a deity	hostile or indifferent to religion
of or relating to clergy bound by monastic vows
concerned with sacred matters or religion or the church
extremely scrupulous and conscientious