St. Augustine speaks about fear: "Let us fear, that we may not fear; that is, let us fear prudently, that we may not fear vainly."
The words of Jesus in this passage reminds his disciples (that means the church too) that to fear what other men may do against the preaching of the gospel is vain in comparison to the trust that we have in God the Father who values us and protects our very souls. Rather than being afraid of those who can harm our body, or harm our reputation, we re to fear our Father in Heave, our Creator, who can end both our lives and our souls. Jesus emboldens his disciples to not fear that which stands against the TRUTH.