Two very distinctive Mediterranean ideas strike the Western reader in this passage: hospitality and human power over the spirit world.
In the ancient world, any person who departed from the family village entered a foreign and hostile world. Death was always and everywhere a threat. Such a traveler had to rely on the kindness of a village elder to extend hospitality and temporary protection from those who intended to harm or kill this stranger (see Gen 18:1-16; 19:1-26). Jesus, therefore, utters a cultural truism when he says to the seventy: “I am sending you as lambs into the midst of wolves”—strangers among nonrelatives (Lk 10:3).
In the peasant world of the Middle East there are no free gifts. Every gift comes with a string attached. A common proverb says: “Don’t thank me: you will repay me.”
Jesus advises his disciples to be discriminating in accepting hospitality on their journey. If the host reciprocates their greeting of “peace,” the disciples should stay there and preach and heal the sick.
On the other hand, if the town insults them by refusing to extend hospitality, they are to go to the town square (a very public place) and publicly return the insult. Both gestures—healing and preaching, and the public insult—bear witness that “the reign of God approaches and is indeed near.”
Our Mediterranean ancestors in the Faith not only recognized a rich and densely populated spirit world, but they also arranged the entire cosmos in a hierarchy as follows: (1) God; (2) gods or sons of God, or archangels; (3) lower non-human persons: angels, spirits, demons; (4) humankind; (5) creatures lower than humankind.
Beings higher on this ladder controlled those beneath them, but sometimes—though very rarely—a lower being could control a higher being. Notice in the New Testament that no one denies the reality of Jesus casting demons out of possessed persons. Rather, they charge that he has no legitimate authorization to use this power (Lk 20:2) or that he has obtained his power from the devil (Lk 11:15).
Jesus, in turn, gave this same power to his disciples. Sometimes it was not effective (Lk 9:40), but in today’s story it seems to have been very effective: “Lord, in your name, even the demons submit to us!” (Lk 10:17).