[OMFG!You'reActuallySmart!]

In the bible, the Apostles were told to eat bread as a representation of Christ's body. So she may have considered it a sin because in no way did you want to eat meat of any form (i.e. considered you a non-believer and spewed nonsense). If anything, not eating bread would be more sinful because that was the actual representation. I've never heard nor seen any Christian condemn another person for this though, so I'm hoping she was just joking. If not, she's the type of Christian who condemns people for whatever mindless stuff. Either way, she was a moron.

Some of the Abrahamic religions discourage eating certain meats because the animals were quite unclean or not cooked properly, so many people became ill and died. From there, some of religions state to not eat that animal. In Christianity, there are some traditions where one a certain day, you shouldn't eat meat or a certain meat, although eating fish is fine. But even then, it's a tradition and not sure if according to the bible it'll lead to being condemned.