Dear Peter:
I'm not sure whether one could have a religious wedding in Germany
without also having a civil marriage. If the civil marriage was
required, then an inquiry to the Standesamt in Magdeburg should produce
results. 1913 is more than 80 years ago, so the records may have been
transferred to the state archives. I haven't been able to find out which
archive in Sachsen-Anhalt would have those, but I'm sure they'd tell you
in Magdeburg.

There are quite a few Jewish records for Magdeburg on film, but there's
a gap for births and marriages between 1903 and 1929, it seems. These
films can be obtained via
https://familysearch.org/eng/Library/FHLC/frameset_fhlc.asp

Magdeburg had a large Jewish community in those days--over 2000 members.
So it's possible there was a newsletter or something like that.

Roger Lustig
Princeton, NJ USA