But as for 2 Catholics who have not done what they’re supposed to do, and chose to defy the rules and marry civilly, well, then their marriage is indeed invalid.
Well, I understand what you’re trying to say, but you’re not
exactly correct. “Valid” or “invalid” has a particular precise meaning in this context. In “invalid” marriage con be convalidated; in this example (two Catholics who marry in a civil ceremony) they are not in an “invalid marriage” – they
can not have their “marriage” convalidated.
If the two Catholics had attempted to follow the proper form, but somehow went wrong (they didn’t use a minister who had the proper delegation to allow him to be the celebrant for the wedding, or they didn’t have two witnesses), then this situation would be known as a “defect of form”.
This can be remedied by a convalidation.
If, on the other hand, the Catholics didn’t attempt to follow the correct form (e.g., they just went to the JP), then the situation is known as a “lack of form”. As I mentioned, this cannot be convalidated, and it’s
not known as an “invalid marriage”. In order to correct this situation, they would need to go to their parish and go through the whole process, making sure that they have no impediments to marriage, that they follow the form, and they exchange consent during a wedding ceremony.
“Living in sin” isn’t a juridical term (to the best of my knowledge), and so, it’s difficult to use it in this context. However, in an objective sense, it
would seem that they’re in a state of grave sin.
Hope this helps…