“But even if you should suffer for righteousness, you are blessed. Do not fear what they fear or be disturbed,” 1 Peter 3:14 HCSB

Peter quotes Isaiah 8:12 at the end of this verse. 

“Do not call everything an alliance these people say is an alliance. Do not fear what they fear; do not be terrified.”

Isaiah 8:12 HCSB

In Isaiah 8:8 we see “It will pour into Judah, flood over it, and sweep through, reaching up to the neck; and its spreading streams will fill your entire land, Immanuel!” HCSB

Why are we to not fear what the world fears? God is with us, Immanuel (Isaiah 7:14,Matthew 1:23). 

“Those who are persecuted for righteousness are blessed, for the kingdom of heaven is theirs. “You are blessed when they insult and persecute you and falsely say every kind of evil against you because of Me.”

Matthew 5:10-11 HCSB