Clue.
Dominus Iesus.
http://www.vatican.va/roman_curia/congregations/cfaith/documents/rc_con_cfaith_doc_20000806_dominus-iesus_en.html
Here, so there's no time wasted:
ANSWERS TO MAIN OBJECTIONS AGAINST DOMINUS IESUS
http://www.ewtn.com/library/Theology/OBDOMIHS.HTM
Is there something in there that negates paragraph 841?