Is vorarephilia a sin

absolutely not, sin is a choice, vorarephilia like any other sexuality is in a duel state of temptation and healthy interest, if a vorarephile kills and eats someone then it is a sin like a perfectly "normal" person raping someone, but just like "normal" people a vorarephile is perfectly capable of maintaining a healthy and happy relationship with their significant other, ultimately nobody chooses their sexuality and if it's not a choice then it can't be a sin, sin is based on what we do with our sexuality, a monogamous and consensual relationship is a gift from God regardless of the nitty gritty details.