An interfaith marriage is defined by most Christian denominations as a marriage between a Christian and a non-Christian, whereas an interdenominational marriage is between members of two different Christian denominations. Denominations may use "interfaith" for both cases, or disagree over whether another group is a Christian denomination or a non-Christian religion. Some denominations forbid interfaith marriage, basing this ban on New Testament verse and the Old Testament verse Deuteronomy 7:3. The Catholic Church has defined criteria on interfaith marriage recognition and the Eastern Orthodox Church also has rules which are similar in most respects. Some Christian denominations impose restrictions on interdenominational marriages.
The Catholic Church requires a dispensation for mixed marriages. The Catholic party's ordinary has the authority to grant them. The baptized non-Catholic partner does not have to convert. Previously the non-Catholic had to agree to raise any children Catholic, but under current rules only the Catholic spouse must promise to do all that is in his or her power to do so. The non-Catholic partner must be made "truly aware" of the meaning of the Catholic party's promise. It is forbidden to have a second religious ceremony in a different religion or one ceremony performed together by ministers of different religions. However, it is possible to waive the requirement of form, so that for example one ceremony performed by the minister of another religion or a civil magistrate will be sufficient. Marriages with members of Eastern Orthodox Churches are valid but illicit without proper observance of the form or dispensation from it, as long as a sacred minister is present and other canonical requirements are observed.
Inter-religious marriages
In 2009, Portuguese Cardinal Jose Policarpo discouraged Portuguese girls from marrying Muslims, due to the fact that it is sometimes difficult to raise children in the faith after a marriage. Marriages between a Catholic and an unbaptized person are not sacramental and fall under the impediment of disparity of worship. They are invalid without a dispensation, for which authority lies with the ordinary of the place of marriage. In addition, the Catholic Church recognizes the Pauline privilege, wherein a Catholic may marry an unbaptized previously married person who consents to convert, but only if the unbaptized person's spouse refuses to become a Catholic also.
