In Christianity ‘the peace that passeth all understanding’ is Presence which is the Nondual state (until you talk or think about it)

“the peace that surpasses all human understanding.”

It is sometimes called nondual awareness. This is just another term for union with God. It is the experience of mystics in the Christian tradition, and it is echoed in other spiritual traditions. It is the Way, the Truth, and the Life that is Jesus Christ.

Photo is by brilliant young photographer Doug Mountford – double exposures on Flickr – see here
https://www.flickr.com/photos/danmountford/