perfidious

Perfidious – adjective, describing a breach of faith or trust, treachery, as in “We were betrayed by a perfidious ally.”

​It comes from Latin perfidia “faithlessness, falsehood, treachery;” from perfidus “faithless;” from the phrase per fidem decipere “to deceive through trustingness;” from per “through,” hence “through” + fidem (nominative case fides) “faith”.

We prayed for the conversion of Jews and Muslims on this Christ the King Sunday, and this caused me to do a little research. The word perfidious in relation to Jews was removed some time ago. Regardless, we must pray and be a good example for Jews and Muslims.