You were blameless in your ways
from the day you were created,
till unrighteousness was found in you.
In the abundance of your trade
you were filled with violence in your midst, and you sinned;
so I cast you as a profane thing from the mountain of God,
and I destroyed you, O guardian cherub,
from the midst of the stones of fire.
Ezekiel 28:15-16 ESV
This is addressed to the king of Tyre, but it obviously doesn’t refer to the human ruler but to Satan, who was the real ruler.
Isaiah tells us how Satan sinned.
“How you are fallen from heaven,
O Day Star, son of Dawn!
How you are cut down to the ground,
you who laid the nations low!
You said in your heart,
‘I will ascend to heaven;
above the stars of God
I will set my throne on high;
I will sit on the mount of assembly
in the far reaches of the north;
I will ascend above the heights of the clouds;
I will make myself like the Most High.’”
Isaiah 14:12-14 ESV
He attempted to take God’s place as ruler of the universe. This began a war that is still going on.
Genesis 3 tells us how we became involved in this war. The first two chapters of Genesis describe how God created a perfect world, free from any trace of sin, and created the first members of the human race, Adam and Eve. In chapter 3 Satan took on the form of a serpent or entered and took control of a serpent and in that form tempted Eve to disobey God. Adam followed Eve in disobedience and this brought the earth and the whole human race under Satan’s control. Here is how we all begin our lives.
And you were dead in the trespasses and sins in which you once walked, following the course of this world, following the prince of the power of the air, the spirit that is now at work in the sons of disobedience—among whom we all once lived in the passions of our flesh, carrying out the desires of the body and the mind, and were by nature children of wrath, like the rest of mankind.
Ephesians 2:1-3 ESV
We start out enslaved by Satan. We are freed from this slavery by repenting of our sins and putting our faith in Jesus Christ. One result of this action is that we become members of God’s army and are now at war with our former master.
Most of the world’s population is on Satan’s side but these people are not our enemies.
For we do not wrestle against flesh and blood, but against the rulers, against the authorities, against the cosmic powers over this present darkness, against the spiritual forces of evil in the heavenly places.
Ephesians 6:12 ESV
We fight Satan by proclaiming the gospel so that others may be freed from Satan’s slavery just as we were.
The Lord’s servant must not be quarrelsome but kind to everyone, able to teach, patiently enduring evil, correcting his opponents with gentleness. God may perhaps grant them repentance leading to a knowledge of the truth, and they may come to their senses and escape from the snare of the devil, after being captured by him to do his will.
2 Timothy 2:24-26 ESV
This war has been going on a least 6,000 years and we have no idea how much longer it will last, but if you read the last part of Revelation you will find that in the end God will win. Surely a war that has been going on so long and involves so many participants deserves to be called The Great War. There is a sense in which it is the only war that has ever taken place. All of the military, religious, and ideological conflicts in human history have been side effects of this war between God and Satan.