What does Revelation 12:7 mean?

In this verse we read about a war that breaks out in heaven. Michael, called "the archangel" in Jude 1:9, and his angels fight against the dragon, Satan, and the dragon and his angels fight back. The Hebrew name Miyka'el is formed as a question: "who is like God?" Michael appears in Scripture as the defender of holiness and all that is good.

Satan is the fourth of seven key individuals listed in this passage: this verse refers to Satan as "the dragon," which is further clarified in verse 9. Satan appears in Scripture as the perpetrator of evil and everything opposed to God. Ephesians 2:2 refers to him as "the prince of the power of the air." We can readily understand why conflict between Michael and Satan breaks out in heaven.

The conflict between good and evil rages today, as Satan attacks believers (1 Peter 5:8). Using trials and temptations, he tries to render believers spiritually ineffective. Paul mentions in 2 Corinthians 12:7 a thorn in his flesh, some kind of severe personal trial, which he calls "a messenger of Satan." Ephesians 6:10–12 reminds us that we are engaged in a vicious warfare with the Devil and his demonic followers.