16 Behold, I
send you forth as sheep in the midst of wolves: be ye therefore wise as
serpents, and harmless as doves.17 But beware of men: for they will deliver you up to the
councils, and they will scourge you in their synagogues;
18 And ye shall be brought before governors and kings for my
sake, for a testimony against them and the Gentiles.19 But when they deliver you up, take no thought how or what
ye shall speak: for it shall be given you in that same hour what ye
20 For it is not ye that speak, but the Spirit of your Father
which speaketh in you.
21 And the brother shall deliver up the brother to death, and
the father the child: and the children shall rise up against their
parents, and cause them to be put to death.
22 And ye shall be hated of all men for my name's sake:
but he that endureth to the end shall be saved.
Craig S. Keener in his "A Commentary on the Gospel of Matthew" wrote:
"Matthew's inclusion of material concerning persecution in his discourse on the kingdom mission indicates his view that persecution and proclamations are inseparable, as does a brief perusal of Acts or Paul's letters. For early Christians, true ministry inevitably involved suffering, especially if that ministry was a frontline ministry to nonbelievers. Yet as Jesus reminds the disciples in the next section, the worst persecutors can accomplish is the disciples' death, and disciples dies anyway with or without persecution…persecution becomes an opportunity for testimony, and the Spirit of prophecy will provide the words they need.
"Sheep were notoriously defenseless against such predators as wolves and Jewish texts often portray God's people in this manner…Jesus drives home the point…his sheep are actually sent among the predators."
In "The Gospel of Matthew: A Commentary on the Greek Text" by John Nolland", there is a discussion of this common usage of sheep in Matthew's gospel:
"Where Luke 10:3 has used 'lambs in the midst of wolves' to emphasize the committed vulnerability which is to characterize the missionaries, Matthew emphasizes instead the external threats to be encountered by the missionaries. Imagery of sheep and wolves has been used in 7:15 of false prophets, and sheep have provided the imagery of sheep without a shepherd in 9:36 and of lost sheep in 10:6…the images function quite separately from one another.
An excerpt from St. Gregory the Great's Moral Reflections on Job:
"Some people are so simple that they do not know what uprightness is. Theirs is not the true simplicity of the innocent: they are as far from that as they are far from rising to the virtue of uprightness. As long as they do not know how to guard their steps by walking in uprightness, they can never remain innocent merely by walking in simplicity. This is why St. Paul warns his disciples 'I hope that you are also wise in what is good, and innocent of what is bad' but also 'Brothers, you are not to be childish in your outlook, though you can be babies as far as wickedness is concerned.' Thus Christ our Truth enjoins his disciples with the words 'Be cunning as serpents and yet as harmless as doves.' In giving them this admonition, he had to join the two together, so that the simplicity of the dove might be instructed by the craftiness of the serpent, and the craftiness of the serpent might be attempered by the simplicity of the dove."
C.S. Lewis also discusses this concept from v.16:
"…Christ never meant that we were to remain children in intelligence: on the contrary, He told us to be not only 'as harmless as doves', but also 'as wise as serpents'. He wants a child's heart, but a grown-up's head. He wants us to be simple, single-minded, affectionate, and teachable, as good children are; but He also wants every bit of intelligence we have to be alert at its job, and in first class fighting trim."