I do it this way. Even pawnbroker rather than shop would convey the wrong idea of greedy money making rather than charitable nonprofit lending.

An object-lesson for the Neapolitan HQ (vs. New York 'branch') of the Camorra.

Translation modelled on Helen P's ref. So Christian-inspired is euphemistc for the anti-Semitic backlash against perceived instances of usury.

NB the mount is in the plural.

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Note added at 1 hr (2016-09-15 12:29:54 GMT)
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http://www.merriam-webster.com/dictionary/eleemosynary

just found in the Net, and never experienced in person. However my choice originates from the following:

though it is true that this institution was founded centuries ago for merciful credit against valuables (and to challenge the Jewish pawnbroking stalls), pls note that now it is in fact a business.... there's an interest rate to pay and fees for belated payments of instalments etc. Unpaid or unclaimed jewelry pieces are auctioned after some time. nd I heard that the origin of the goods deposited cannot be checked and sometimes it is not water-clear.... In Rome the Monte di Pietà is rather famous, has its own square with its name just in front of the jewish ghetto and it is managed by a major bank.

I would give the (established) literal translation and then add a gloss in brackets.