Yes, even people without religious faith talk glibly of the departed being "at peace" "at rest" etc.
If there is no afterlife, if you just plain STOP, then there is no peace, because there has to be something of you to know that it is peaceful after all. I have long believed that the human being has an innate fear of annihilation, of ceasing to exist, entirely, nothingness. Give it a 5 minute whirl, close your eyes, lean back in a comfy chair, and imagining not existing in any way at all - except in memories - but what is the use if you are not around to enjoy them?