If we come to know after consummating a Mutah marriage that the girl was a Hindu or Buddhist or Sikh or Christian, then what should we do now?
Mut'ah marriage is a type of marriage in Islam which is permissible with Muslim woman or a woman from the People of Book under some conditions. No Mut'ah marriage can be allowed with non Muslim woman who is not from People of Book. If you discover that she is non Muslim, and not from People of Book, it means that there is no Mut'ah marriage at all and it will be Haraam to remain with her.
Wassalam.