Answer:
   
   In 1909 the CCAR held that intermarriage (interfaith marriage) is
   ``contrary to the traditions of the Jewish religion.'' The same
   position was restated in 1947, and amplified in 1973, when a
   substantial majority at the CCAR Convention in Atlanta ... declared
   its opposition to participation by its members ``in any ceremony which
   solemnizes a mixed marriage.''
   
   Outgoing UAHC president Alexander Schindler supports the stance
   because of the threat he believes intermarriage poses to the future of
   Judaism."
   
   Most rabbis justify their refusal to officiate at interfaith weddings
   by arguing that the Jewish conception of marriage is that of a
   covenant between two Jews. However, in the United States, there are a
   number of Reform rabbis (one estimate is about one-third) that do
   perform such ceremonies, under the belief that it is better to not
   create an atmosphere of rejection, which can only serve to turn away
   and alienate the Jewish partner. If the Judaism of the Jewish partner
   is strong, the non-Jewish partner is often turned towards Judaism and
   the children are raised Jewish.
   
   Note even if a Reform Rabbi does not perform an intermarriage, they
   will usually accept the marriage as valid, and regard the children of
   those marriages as Jewish as long as they are raised as Jews.
   
   It should be noted that few, if any, Reform/Progressive rabbis will
   perform an intermarriage in either Canada or the United Kingdom.