Synonyms for FAVOR: kindness, service, indulgence, good turn, grace, approbation, befriending, favour; Antonyms for FAVOR: disfavor, opposition, disapproval, dislike, misprize, disesteem, abuse, bear a grudge against.

Here's a list of opposite words from our thesaurus that you can use instead. “Doing him a disfavor would be sure to bring the vultures swooping down on his business.” “Secularism was accepted to ensure equal rights and impartiality towards all religions.”