Jesus described the Twelve the same way he described those to whom he sent them—as sheep. “The lost sheep of the house of Israel” were defenseless, vulnerable, and endangered. The Twelve were likewise just as defenseless, vulnerable, and endangered as those to whom Jesus sent them.
In his instructions to the Twelve, Jesus insisted that they be “as harmless as doves” (v. 16). He prohibited them from carrying a stick (v. 10), often used by people of modest means to protect themselves. In those days, a walking stick was also a “whacking stick.” (The disciples, then, going from town to town on foot, would do a lot of walking, but they wouldn’t be doing any whacking.) And Jesus apparently didn’t ascribe to the law of “stand your ground” either: when persecuted, he commanded the disciples not to stand their ground, but to cut and run (v. 23).
Was Jesus so opposed to self-defense? Was he so rigorous in his commitment to non-violence? Was he so averse to his followers standing up for themselves? After all, he did famously counsel his followers to turn the other cheek (5:39). Yet he himself said that he was not bringing peace but “a sword” (v. 34), and later in Jerusalem raised a ruckus in the Temple (21:12). So then, among the exegetes and the ethicists, the jury is still out.
But what is key here is that the disciples were sheep sent to sheep, and so sent as sheep. Sheep have no fangs or claws, and the Twelve were like unto them. Had they the fangs and claws of a wolf, they would invariably, intentionally or not, wind up biting and clawing those to whom Jesus had sent them. In his instructions, Jesus went out of his way to reduce the chances that such injuries might happen.
Jesus took special care to instruct his disciples to go to the lost sheep of the house of Israel in such a way that they would be like them, share in their vulnerability, and in no way do them any harm.