Many believers live in unfounded fear always anticipating what the devil might do. This fear and anticipation of evil eventually materialises thereby reinforcing the validity of the fear in the first place (Job 3:25). Many are ignorant that they are snared by the words of their mouths (Proverbs 6:2).
God has not given us the spirit of fear; but of power, love and a sound mind (2 Timothy 1:7). There is no basis for the fear of the devil. Of course the facts about him (the devil) are true -- (a) he is powerful but greater is He that lives within us (1 John 4:4). (b) he is always roaring about seeking whom he can devour but we dwell in the secret place of the Most High and abide under the shadow and strong tower of the Almighty (1 Peter 5:8,9; Psalm 91:1-3; Proverbs 18:10).
The enemy and his agents know that the godly are secure in the Rock of their salvation. However they try to play down the reality of this security, prevent us from full knowledge of our place, position, privilege and power in Christ. Whatever might have been your understanding of the believer's position, it will be well to know afresh that “SURELY there is no enchantment against Jacob, neither is there any divination against Israel”.