Will a remarriage send someone to hell if they do not repent?

Well it depends on what you get divorced for for it to be unlawful or not, the bible states for divorce that can only be acceptable only if one mate has cheated on the other or if the mate dies then the other can remarry if they choose. But there are obvious reasons for separation like abuse and such, but i guess you could say its possible if they remarry outside scriptural bounds.