In the book Karma is Negotiable (by Nikias Annas), it is written that "cancer is caused by fornication." What about the case of a smoker who gets lung cancer? That's just one example of how many different things can cause cancer. Since virtually everyone on our planet is guilty of fornication, it would mean that virtually everyone gets cancer, but we know that's not the case. I've encountered different definitions of the unforgivable sin against the Holy Spirit among different Gnostic groups.