backslider vs offender

backslider and offender both are nouns.

Word	Noun	Adjective	Verb	Adverb
backslider	Yes	No	No	No
offender	Yes	No	No	No

As nouns, offender is a hypernym of backslider; that is, offender is a word with a broader meaning than backslider:

backslider: someone who lapses into previous undesirable patterns of behavior
offender: a person who transgresses moral or civil law

Other hypernyms of backslider include wrongdoer.

backslider (noun)	offender (noun)
someone who lapses into previous undesirable patterns of behavior	a person who transgresses moral or civil law