Fear

"Then some came and told Jehoshaphat, saying, 'A great multitude is coming against you from beyond the sea, from Syria; and they are in Hazazon Tamar' (which is En Gedi). And Jehoshaphat feared, and set himself to seek the Lord, and proclaimed a fast throughout all Judah."  2 Chronicles 20.2-3

The devil works with a threatening word, to spread fear, and especially terror. He does not usually use the opponents as much as he does the people who are closest to us. That's right. He often uses those in which we trust most. However it may be, as the example of Jehoshaphat, when terror comes, start seeking the Lord and fasting immediately. The spirit of fear does not stand.

THE AUTHORITY OF FAITH

"Therefore I write these things being absent, lest being present I should use sharpness, according to the authority which the Lord has given me for edification and not for destruction."     2 Corinthians 13.10

While doubts give evil the authority to spread terror and destruction, supernatural faith has the authority of God to save those who believe. 
The servants of evil spread doubt and death.
The servants of God sow faith and life.