The twentieth-century English mystic Caryll Houselander (1901–1954) describes how an ordinary underground train journey in London transformed into a vision that changed her life. I share Houselander’s description of this startling experience because it poignantly demonstrates what I call the Christ Mystery, the indwelling of the Divine Presence in everyone and everything since the beginning of time as we know it:
All sorts of people jostled together, sitting and strap-hanging—workers of every description going home at the end of the day. Quite suddenly I saw with my mind, but as vividly as a wonderful picture, Christ in them all. But I saw more than that; not only was Christ in every one of them, living in them, dying in them, rejoicing in them, sorrowing in them—but because He was in them, and because they were here, the whole world was here too . . . all those people who had lived in the past, and all those yet to come.
I came out into the street and walked for a long time in the crowds. It was the same here, on every side, in every passer-by, everywhere—Christ.
I had long been haunted by the Russian conception of the humiliated Christ, the lame Christ limping through Russia, begging His bread; the Christ who, all through the ages, might return to the earth and come even to sinners to win their compassion by His need. Now, in the flash of a second, I knew that this dream is a fact . . . Christ in [humankind]. . . .
I saw too the reverence that everyone must have for a sinner; instead of condoning his [or her] sin, which is in reality [their] utmost sorrow, one must comfort Christ who is suffering in [them]. And this reverence must be paid even to those sinners whose souls seem to be dead, because it is Christ, who is the life of the soul, who is dead in them; they are His tombs, and Christ in the tomb is potentially the risen Christ. . . .
Christ is everywhere; in Him every kind of life has a meaning and has an influence on every other kind of life. . . . Realization of our oneness in Christ is the only cure for human loneliness. For me, too, it is the only ultimate meaning of life, the only thing that gives meaning and purpose to every life.
After a few days the “vision” faded. People looked the same again, there was no longer the same shock of insight for me each time I was face to face with another human being. Christ was hidden again; indeed, through the years to come I would have to seek for Him, and usually I would find Him in others—and still more in myself—only through a deliberate and blind act of faith. 
I (Richard) would say that my only real definition of a Christian is one who can see Christ everywhere else and even in oneself.