Should Christians Fear The Devil and His Demons?

The Bible says that Satan prowls like a roaring lion seeking someone to devour (1 Peter 5:8). Does this mean Christians should be afraid of Satan or does this mean we should be ready for when he and his demons attack?

John MacArthur tells us what power the devil and his demons have and where our ultimate victory lies:

Demons possess the great power of angels (Rom. 8:38; 1 Cor. 15:24), greater than humans but far less than their Creator. They have the power to carry out the following actions:
1.Indwell humans and animals (Mark 5:1–16)

2.Physically afflict people (Mark 9:17, 22)

3.Terrorize humans (1 Sam. 16:14–15; 18:10; 19:9; Acts 19:13–16; 2 Cor. 12:7)

4.Initiate false worship (1 Cor. 10:20–21)

5.Promote false doctrines (1 Tim. 4:1)

6.Perform false signs and wonders (2 Thess. 2:9; Rev. 16:13–14)

7.Deceive prophets (1 Kings 22:19–23)

8.Encourage idolatry (Deut. 32:17; Ps. 106:37)

9.Engineer death (Judg. 9:23, 56–57)

Demons work from a powerful heavenly hierarchy to execute their evil deeds. Words such as “angels,” “authorities,” “cosmic powers,” “dominions,” “powers,” “rulers,” and “thrones” can be used to describe the hierarchies of either holy or evil angels. In context, Romans 8:38; 1 Corinthians 15:24; Ephesians 2:2; 6:12; and Colossians 2:15 most likely refer to various ranks or levels among the evil angels, that is, the demon hierarchy. In context, Ephesians 1:21; Colossians 1:16; and 1 Peter 3:22 most likely refer to various ranks or levels in the holy angel hierarchy.

Scripture never elaborates on the specifics of these hierarchies to explain their order or function. Since Satan imitates and falsifies God’s character and kingdom characteristics, it is most likely that there is both an authoritative functional hierarchy for holy angels who worship God and a parallel counterfeit hierarchy for evil angels who give their allegiance to Satan.

However strong demons might be, they also have serious weaknesses and vulnerabilities:
1.They unwittingly serve God’s purposes (Judg. 9:23).

2.They were terrified of Christ and the gospel (Matt. 8:29; Mark 1:24; James 2:19).

3.They obeyed Christ (Matt. 8:32).

4.They obeyed the Twelve (Matt. 10:1–8) and the Seventy-Two (Luke 10:17–20).

5.They cannot separate believers in Christ from the love of God (Rom. 8:38).

6.They can be restrained by the Holy Spirit (2 Thess. 2:6; 1 John 4:4).

7.They have been judged already by God (2 Pet. 2:4; Jude 6) and will be again in the future (Rev. 20:10).

Adapted from Why We Should Not Fear Satan and Demons which is based on MacArthur's book, Biblical Doctrine: A Systematic Summary of Bible Truth