Wonderful little illustration from Peter Martyr Vermigli. He says:
In human affairs, a husband sometimes happens to journey to a distant land, leaving his wife at home for a time, yet continuing to be (as Scripture says) one flesh with her. Their true, proper and lawful union remains perfect, though the one is absent from the other. How much more does Christ – husband of the church, as the Apostle says – remain united with his members though gone away into heaven and departed in body?
This could easily be developed in various ways in a sermon context. Vermigli applies it in a debate with Lutherans and others over the issue of the ubiquity of Christ’s human nature (in his address to the Strasbourg Senate). For him, as for Calvin and many puritans too, following Ephesians 5, marriage was a great illustration of union with Christ.