Christian vs religious person

Christian and religious person both are nouns.

Word	Noun	Adjective	Verb	Adverb
Christian	Yes	Yes	No	No
religious person	Yes	No	No	No

As nouns, religious person is a hypernym of Christian; that is, religious person is a word with a broader meaning than Christian:

Christian: a religious person who believes Jesus is the Christ and who is a member of a Christian denomination
religious person: a person who manifests devotion to a deity

Christian (noun)	religious person (noun)
a religious person who believes Jesus is the Christ and who is a member of a Christian denomination	a person who manifests devotion to a deity

Christian (adjective)	religious person (adjective)
relating to or characteristic of Christianity