Ken,

Catholics recognize the marriages of most other persons, with a few exceptions, such as same-sex unions. It can be a complex matter, with several different criteria involved, but in a very general sense, yes, most marriages are recognized and therefore those persons are not living in sin, but to the contrary are expressing love in a very deep sense, provided they are given to each other fully, honor their life-giving power and build each other up.

For the general view on marriage please check out the section on Marriage from the Catechism of the Catholic Church below:

• Article 7 The Sacrament Of Matrimony [Bishop's web site|St. Charles Borromeo version]

Peace,

Bob Kirby

Dear Ken,

You said:

• Do Roman Catholics believe that a marriage that is not in the Roman Catholic Church but is legal in one's state or country, is a valid marriage?

We need to make a distinction.

• Does the marriage involve a Catholic (or an Orthodox person)?
  
  
• If it does, and therefore the Catholic gets married only civilly, then the marriage is invalid.
• If the marriage does not have a Catholic involved (i.e. two Jews, two Lutherans, two people with no religion, etc.) then the civil marriage is considered valid.

You said:

• If the marriage is not recognized as valid by the Church but viewed as legal in one's state or country, do they believe that the couple is living in sin?

Assuming the couple in that situation are having sexual relations with each other, then the answer is yes — the Catholic is living in sin.

Fr. Jonathan