Rev. William Weedon offers a great quote from C. F. W. Walther, the father of the Lutheran Church Missouri Synod (the reference being to an excellent devotional book drawn from Walther’s writings translated by Gerhard Grabenhofer, one of my former students!)
Each rejoices when another rejoices, and each regards himself as a greater sinner than another. He is therefore honored to receive a visit from even the humblest Christian, for he knows this individual carries within himself the Spirit of the Lord Jesus Christ, just as Mary carried Jesus bodily in her womb. He also knows that, in his fellow Christian, Christ is making a visit. – *God Grant It!* p. 907
Notice the theology of Christ’s presence in ordinary people, which is basic to the doctrine of vocation.