Why is marriage outside of the Church not recognized?

[Elzee]

A friend of mine is in RCIA and the facilitator was not able to answer this question. I would like to be able to give an accurate exaplanation. Any scriptural support would be helpful also. I’ve checked the CCC, but I can’t seem to find anything that very directly explains ‘why’.
It’s a very basic question:
Why does the Catholic Church not recognize as valid the marriage of a Catholic (to either a non-Catholic or another Catholic) who is married outside the church?

 

[Fr.Vincent_Serpa]

Dear Elzee,

Unlike most Protestant churches which see marriage as simply a contract made by two people for life, the Catholic Church recognizes marriage as a sacrament. Marriage is therefore an outward sign instituted by Christ to give sanctifying grace. All sacraments come under the authority of the Catholic Church. As with all the other sacraments, the Church determines the requirements for the validity of the sacrament of matrimony. It therefore requires that Catholics be married according to the “form” of the celebration of this sacrament. This form requires that the marriage of Catholics be contracted in the presence of a bishop, priest or deacon. Exceptions can be made in certain circumstances, but only at the discretion of authorities of the Catholic Church. (Canon 1108) Only Catholics are bound by this form. The Catholic Church does recognize the validity of marriages by non-Catholics with each other. Catholics are held by a higher standard in conformity with the higher understanding that Catholics have of marriage.

Fr. Vincent Serpa, O.P.