Yes, "Perfidious" Is Fitting

Well, well, well.

Alexander ‘Shabbos’ Kestenbaum — Jewish activist who was given a prime speaking slot at the Republican National Convention and a front row seat to a Donald Trump speech just last week — is now at the Democratic National Convention touting himself as a “pro-Israel Democrat” seeking to “restore the soul” of what he calls “our party.”...

As to "perfidious":  IYKYK.  

But you could Google that word + 'Benedict XVI'  if you really want to know.