What does the clause "quae suae salvationis causa exstitit" mean?

Question

I'm having difficulty parsing the following sentence from Alfonsi's Dialogi contra Iudaeos, particularly the clause in bold:

Dies Dominica, dies, viz. resurrectionis, quae suae salvationis causa exstitit, Christianorum Sabbatum est.

This is most likely due to my lack of diligence in Latin studies, so apologies for that. But here's what I have:

• quae: plural neuter pronoun (probably accusative?)
• suae: plural possessive pronoun
• salvationis: noun, 3rd declension, singular genitive
• causa: "on account of"
  • My Latin dictionary gives "in abl. with gen. or posses. adj. (usu. put after the noun)"
• exstitit: verb (3rd), third-person singular

My rather wooden literal translation, then, would be:

The Lord's day – the day, that is, of the resurrection, on which account their [Christians'] salvation emerges – is the Christians' Sabbath.

I'm sure there are multiple issues here, but I'd like to focus on these:

• I'm not sure that my understanding of suae here is correct. I believe christianorum could be either the genitive of the noun christianus, or an adjective, and I wonder if suae or other context indicates which. That is, is christianorum sabbatum "the Christian Sabbath" or "the Christians' Sabbath," or both/either?
• Is there some point to combining suae and a genitive noun? Don't we know who possesses the salvation without suae?
• How does causa fit into this?

---

^{This line from Alfonsi's work is widely quoted online, but I haven't been able to find the complete text that would include the broader context. An English translation is available on Google Books, however; Page 257 seems to include the text in question, but it translates it much differently, which is part of the reason for my confusion:}

^{It was no longer necessary for all those believing in him to observe the Sabbath but to observe Sunday instead, namely, the day of the Resurrection, which was the basis of their salvation.}

Answer 1

The key confusion seems to be with quae. It is here the singular feminine nominative relative pronoun. I think it refers to resurrectio; there is also a reading which relates it to dies (Dominica). See below.

It seems most likely that suae refers to Christians. As pointed out in a comment below, this is somewhat unusual. Usually suus refers to the subject of the clause, but this is clearly not the case here.

I would translate like this:

resurrectio, quae suae salvationis causa exstitit
resurrection, which happened for the sake of their salvation

The only word giving details of salvation is suae; without it we would not know who "owns" the salvation. Causa is an ablative and in my translation it corresponds to "for the sake". Notice also that exstitit is perfect tense. Present tense would be ex(s)istit.

Christianorum must mean "of the Christians". (Sabbatum Christianum would be "Christian Sabbath".) It probably modifies sabbatum, but it is also possible to read it as modifying resurrectionis. Context rules it out if I understand correctly but grammar does not. This leaves to two translation options:

Dies Dominica, dies, viz. resurrectionis, quae suae salvationis causa exstitit, Christianorum Sabbatum est.
1. The Lord's day, the day of resurrection, which happened for the sake of their salvation, is the Christians' Sabbath.
2. The Lord's day, the day of Christians' resurrection, which happened for the sake of their salvation, is the Sabbath.

You can also include viz., but I found it more fluent to leave it out.

If quae refers to dies (Dominica), we have something like this:

Dies Dominica, dies, viz. resurrectionis, quae suae salvationis causa exstitit, Christianorum Sabbatum est.
The Lord's day, the day of resurrection, which emerged due to their salvation, is the Christians' Sabbath.

Option 2 from above can also modified to this case. Now the relative clause describes "The Lord's day, the day of resurrection" instead of "resurrection". There is probably a way to phrase that less ambiguously in English.