Saint (Mother) Teresa of Calcutta always talked about seeing Christ “in His distressing disguise of the poorest of the poor.”
Seeing Christ in others, in my opinion, is about serving Christ through our service to them, loving Christ in our loving actions towards them.
Sometimes, Christ reveals Himself in the beautiful, loving actions of others, or through their wisdom.
I try to be the love of God in word and action to my students, their families, and my colleagues, to my family and friends, and even strangers in a store. Christ has no body now but ours.
And the religion of the other person has nothing to do with anything. God has spoken to me through my atheist friends as well as – or even better than – my Christian friends.