EWTN Catholic Q&A
Question from Anon on 10-26-2012:

I was just wondering how philosophy can explain the differences between a Catholic marriage and another marriage , say at the registrar's office.What underlying truth exists about the reality of these two? How about another Christian marriage? If a marriage between a Catholic and another Catholic is made a holy union by God, isn't God's Spirit the same that makes holy those of other Christians?

Answer by Richard Geraghty on 11-09-2012:

Dear Anon,

Marriage is both a natural institution founded by God and a supernatural institution founded by Christ. Marriage in the Catholic Church is the fullness of marriage. Baptized Christians share in this fullness. But the ideal is a Catholic marriage because it is one of the seven sacraments.

Dr. Geraghty