Mark,
I’ll point you to https://en.wikipedia.org/wiki/Rest_in_peace The Latin phrase is used in the Tridentine Requiem Mass several times. Perhaps I should have phrased that as
‘requiescat does not simply mean rest’ but is the opening of a prayer offered for the soul of the dead. Of course the modern English RIP does not have this connotation for secular people. But respect is surely indicated in either case.
Longer explanation here: https://www.funeralhelpcenter.com/what-does-rip-actually-mean/
Derek