This question already has an answer here:
How does Catholicism handle the desired marriage of a Catholic to a baptized, yet non-Christian partner?
As I understand it (i.e.: what Wikipedia told me), the Catholic church defines three versions of the Sacrament of Marriage:
"Canonical" marriage: an unmarried man and woman, each a baptized Catholic of age, are married by a Catholic cleric. The marriage is considered valid and sacramental.
"Mixed" marriage: one of the couple is a baptized non-Catholic Christian. Catholic marriage is still possible, but requires the special permission of a Catholic cleric. With this permission, the marriage is also considered valid and sacramental.
Disparitas cultus marriage: one of the couple is an unbaptized non-Christian. Catholic marriage is discouraged, but still technically possible via dispensation of disparitas cultus by a Catholic cleric. This dispensation can only be acquired if three conditions are fulfilled:
- The Catholic party is allowed free exercise of their religion.
- All offspring are to be raised as Catholics.
- The Catholic member of the couple promises to do "all that is possible" to convert the non-Catholic member to the Catholic religion.
The marriage is then considered valid, but is not sacramental (instead considered "natural" marriage).
First off - are there any glaring errors in my understanding of Catholic marriage?
Second - what I find lacking from this definition is the case of a baptized non-Christian seeking marriage to a Catholic. My first thought was that this would fall under disparitus cultus marriage; the lack of one party's Christian faith would "invalidate" their baptism. However, this reasoning is clearly wrong; the Catholic church also holds that Baptism is "indelible" and cannot be repeated or undone [CCC 1280]. Given this belief (and the fact that the Catholic church does appear to recognize non-Catholic baptism under at least some conditions [CCC 1256]), what happens when one of the parties was baptized but is no longer a practicing Christian?