[And] do not fear those who kill the body but cannot kill the soul. Rather fear him who can destroy both soul and body in hell. —Matthew 10:28
In our passage Jesus sends his disciples into hostile environments (Matthew 10:17-19), and seems to presume that his disciples will have fear toward someone, either those who kill the body but not the soul (i.e., people) or the One who can destroy both (God) in hell.
“Fear” here is like that of Proverbs (1:7, 9:10; 29:25; etc.) in that it involves a reverence and respect that has a decisive influence on our behavior. Notice the limitations of human authorities Jesus presumes. Surely they “kill the body.” Though elsewhere Jesus says can (or cannot) kill, but here he simply says “kill.” Perhaps he assumes that they do in fact do it already, and the disciples know about it. Yet the influence of the killers is severely limited. They cannot touch the soul. The exhortation not to fear people is due in part to the inabilities or very limited extent of their influences. Their jurisdiction is limited only to physical and bodily life and well-being, not to heavenward things, such as the soul of a believer in Christ (cf. Matthew 6:19-21).
This exhortation not to fear them is contrasted (“rather”) with an exhortation Who disciples are to fear: God. Nowhere is God’s name said in this verse. Yet the contrast is clear enough by the extent of the person’s influence. In contrast to human authorities, the One whom disciples are to fear “can destroy”—note the indication of ability, in contrast to that of human authorities—not simply the body (as in the human authorities), but also the soul (which the human authorities cannot touch). The location of God’s destruction of some is “in hell.” It is God alone who has jurisdiction over such outcomes, and therefore He alone is to be feared in every aspect of life, particularly our witness to others.