I want to give a shiur in Shul about Shabbat and how it Rambam and others say that one gets Kares if one doesn't keep it and it says in the Chumash 'that he is cut of from his people'.
A person came up to me and got annoyed saying I was a fundamentalist and says that it means that you are cut off from your community, not in the afterlife and that Kares doesn't mean you lose your afterlife. I quoted him the Rambam and he said that Rambam wrote a book 10 years later contradicting himself?
My questions is, what does Kares actually mean? and do you have any sources/names of rabbi's?