What It Is
The Bible tells us that there is a spiritual battle going on between good and evil. It speaks of this spiritual battle in many places, but one of the most common verses on this topic is from the apostle Paul in Ephesians 6:12.
Ephesians 6:12 For we do not wrestle against flesh and blood, but against principalities [authorities], against powers, against the rulers of the darkness of this age, against spiritual hosts of wickedness in the heavenly places.
2 Corinthians 10:3-4 also explains what this warfare is, and makes it clear that Christians aren’t engaged in a physical battle but a spiritual one.
2 Corinthians 10:3-4 For though we walk in the flesh, we do not war according to the flesh. For the weapons of our warfare are not carnal but mighty in God for pulling down strongholds.
What is the purpose of this spiritual battle? It’s a battle that Christians need to fight in order to protect our hearts and minds from the influence and attacks of Satan.
Satan’s number-one enemy is Jesus, and he makes it a priority to try to defeat those who believe in Him. He will do what he can to get in the way of your relationship with Jesus and to stop you from being an effective Christian—one who brings more souls into God’s kingdom and influences the lives of others for good.
Every time you bring Jesus’ truth and salvation to others, there is no doubt that you will take part in this spiritual battle of good against evil.
How It All Began
There is the side of good, which is God and His heavenly forces, and there is the side of evil, which is the Devil and his demons. These two sides have been at war since the creation of the world, and have been looking to influence the souls and minds of those on earth to affect the course of history.
However, God and Satan weren’t always at war. There was a time when Satan was on the good side; he was God’s right-hand man and was known as Lucifer. Before Lucifer became Satan, he was an incredibly beautiful creature, created out of precious stones and musical instruments. (Read Ezekiel 28:12-19 for a fuller description of Lucifer.) In Ezekiel 28:12 God said of Lucifer, “You were the seal of perfection, full of wisdom and perfect in beauty.” Sounds rather awesome!
Apparently Lucifer thought so as well, as his beauty eventually became his downfall. God said of him, “You were perfect in your ways from the day you were created, till iniquity was found in you.”  And what was that iniquity? It was pride. “Your heart was lifted up because of your beauty.” 
Lucifer first became proud because of his utter perfection, which then led to his pride in thinking that he could be equal to God.
Isaiah 14:12-15 How you are fallen from heaven, O Lucifer, son of the morning! How you are cut down to the ground, you who weakened the nations! For you have said in your heart: 'I will ascend into heaven, I will exalt my throne above the stars of God; I will also sit on the mount of the congregation on the farthest sides of the north; I will ascend above the heights of the clouds, I will be like the Most High.' Yet you shall be brought down to … the lowest depths of the pit.
From the day that Satan fell, he has been hard at work trying to prove God and His laws and principles wrong, both in the heavenly realm and here on earth. And for us on earth, this great battle between good and evil all began in the Garden of Eden, when Satan convinced Eve to eat a fruit from the Tree of the Knowledge of Good and Evil.; 
The Battle Between Good and Evil
Each day we’re faced with choices. When you have a run-in with one of your friends or a member of your family, you can either choose to work things out nicely or you can choose to argue and give each other a hard time. This is an example of the inner struggle between good and evil that we’re often confronted with.
It isn’t always easy to make the choice for good, because it’s within our human nature to get angry, frustrated, or to say the first mean thing that comes to mind. This is why we need Jesus to help us to take on His nature, so that we can more easily choose to have the right reaction, the loving reaction.
In a story from Native American folklore, a grandfather explains to his young grandson the inner struggle between good and evil.
"A battle goes on inside us all," the grandfather begins. "It is a battle between two wolves. One wolf is the embodiment of everything evil, like hate, anger, jealousy, resentment, greed, arrogance, lying, and selfishness. The other wolf is the embodiment of everything good, like love, joy, peace, hope, serenity, humility, kindness, empathy, generosity, compassion, truth, and faith."
The grandson thinks about those words and then asks, "Which wolf wins?"
The grandfather replies, "The one you feed.
Whenever you have a thought that causes you to feel angry toward someone, or bitter, unhappy, or critical, you are giving the evil wolf a good meal. How much better to make the good wolf stronger by feeding it kind, forgiving, positive, and constructive thoughts and actions! The more you feed the good wolf, the stronger he will grow.
The good news is that if you are staying close to God, then without even knowing it, you will be “feeding that good wolf.” Wherever God exists, the Devil cannot exist, because darkness cannot coexist with light.
Watch it: Evil is the Result of Men Not Having God in Their Heart
Knowing Who’s Who
We can tell the difference between God's good spiritual forces and the Devil's evil spirits by "test[ing] the spirits, whether they are of God." 
God’s power is creative and loving, while the Devil's power is destructive and hateful. God's Spirit ministers love, joy, peace, longsuffering, kindness, goodness, faithfulness, gentleness, and self-control—all good things. The Devil and his evil spirits minister fear, hatred, bitterness, strife, misery, confusion, and torment—all bad things. 
There is, of course, the good side to the spirit world—the side that fights the Devil and those who follow him. This side not only includes God, Jesus, and the Holy Spirit, but also other spirits as well. You can find reference to these spirits in the Bible.
These include the seven spirits of God spoken of in Revelation 4:5, the seven stars or angels or spirits of the seven churches of Revelation 1:20, the four spirits of the heavens of Zechariah 6:5, and the multitudes of other celestial messengers, angels, or spirits that are mentioned in the Bible.
The apostle Paul calls this heavenly host a "great cloud of witnesses" that surrounds us.  Just like a cloud is composed of millions of tiny particles of moisture, this spiritual cloud is composed of millions of good spirits.
In the book of 2 Kings we learn about how God opened someone’s eyes to see into the spiritual realm and he got a glimpse of some of those many witnesses:
2 Kings 6:15-17 (NIV) When the servant of the man of God got up and went out early the next morning, an army with horses and chariots had surrounded the city. "Oh, my lord, what shall we do?" the servant asked. "Don't be afraid," the prophet answered. "Those who are with us are more than those who are with them." And Elisha prayed, "O Lord, open his eyes so he may see." Then the Lord opened the servant's eyes, and he looked and saw the hills full of horses and chariots of fire all around Elisha.
They are not only watching us, they are watching over us, protecting us, and trying to influence us for good. All throughout the Bible there are many promises of spiritual protection, such as, "The angel of the Lord encamps all around those who fear Him, and delivers them,"  and, "He shall give His angels charge over you, to keep you in all your ways." 
These heavenly beings are also there to help us to fight the battle of good and evil mentally and spiritually, and to help us to choose what is right over what is wrong.
Strategy Against Satan's Tactics
The Bible tells us to “fight the good fight of faith”  and warns us not to be ignorant of the Devil’s tactics. The Devil has no direct power over us physically, but he can try to influence our thoughts, attitudes, and decisions. We don’t need to fear him, but we do need to be on guard against him.
The Devil knows that if he’s too obvious with his attacks, then we would readily recognize his lies and know how to defeat him. So he often uses more subtle tactics, like twisting the truth to cause us to choose to do something wrong, or magnifying our lazy nature to keep us from choosing to make a positive decision.
Say you became sick or were involved in an accident. You feel that if you would have done something differently, this wouldn’t have happened. As a Christian, you know that God can use this situation to either teach you something good or bring you closer to Him. Once you have asked Him and have done your part to get His thoughts on the matter, then that’s that—you get better and move on. But the Devil is more than happy to play on your feelings of remorse. He will try to make sure that you don’t let go of that bad feeling, and he does his best to make sure that you will continue to beat yourself up about what you did wrong for as long as possible.
The goodness that Jesus gives us makes us feel forgiven, humbled, and thankful, so if you are instead carrying feelings of remorse, condemnation, and regret, you need to realize that this is Satan at work.
It’s important to recognize the thoughts and lies of Satan, because once you do, you can then access the power and promises of Jesus that He gives you through the words that are written in the Bible. The Devil cannot withstand the power of Jesus. His own power is weakened and he is then easily defeated.
Listen: Fight Like a Warrior
Fight Like a Warrior
A message from Jesus
The true warrior is always looking for a way to gain territory no matter how severe the attacks of the Enemy may be. Unlike earthly warfare, where you often retreat when casualties are high, or you concede defeat because you're badly beaten, when it comes to spiritual warfare you never need to concede defeat, because you can always rely on Me to come through for you, and make every situation and every battle a victory situation if you never give up.
The way of man is usually to pull back in certain areas in order to reinforce other areas where major attacks have been launched, but that's a very defensive approach. Often the best way to fight back is to not only stand your ground, but to launch an attack in several directions, so that the Enemy is the one who is then put on the defensive and sent running.
No matter how badly the Enemy attacks you, you have the power and the weapons to keep hammering away at him. You have the heavenly resources to keep blasting his forces to bits. And you have the gift of faith to hold tightly to, so that no matter how dismal the outlook may be, your faith in Me will sustain your spirit with the promise that I will be the victor, so long as you are willing to keep fighting and seeing the battle through.
Don't give the Enemy the pleasure of seeing you pull back because of his scare tactics. Keep launching your attack. Keep sending volleys into Satan's camp, no matter how hard he's besieging you. The courageous man is the one who keeps fighting and moving forward even when he's hardest hit, even when there are foes all around and the battles are intense. There is always hope of victory if you keep fighting.
Watch it: Skit on the Devil's Tactics
The Armor of God
In order to resist and fight Satan, Jesus has given us spiritual armor and spiritual weapons to use, which gives us strength to withstand his attacks. We must remember that the war of good and evil is not a carnal one but a spiritual one—one that can only be won through mind and spirit. And also one that is won through faith and belief in God’s Word.
Breakdown of God’s Armor
What do we need for protection?
We are fighting the devil—Satan. We are not fighting people, but the powers of darkness in this world, which is Satan and his helpers. The protection we need is the armor of God.
What is the armor of God, and how can we clothe ourselves in it? Let’s look at each piece.
Belt of truth—Standing firm in truth. Living our lives by the truth of God’s word.
Breastplate of Righteousness—Walking uprightly before God. Aligning our lives to His standards.
Shod feet—Standing with firm-footed stability, being ready.
Shield of Faith—Standing firm in our faith. This will squash all the fiery darts Satan sends.
Helmet of Salvation—Protection for our minds. Satan attacks us here more than anywhere. We need to be sure of our Salvation and not waver or doubt.
All of these pieces are for protecting us—and need to be put on daily.
There is still one other piece we need to be armed with. This piece is not for protecting us, but for fighting with.
The Sword of the Spirit—which is the word of God.
We cannot fight the enemy if we don’t know the word of God. It is vital for how effective we are when we use the sword, and how effective the rest of the armor is that protects us. No soldier goes to war with faulty weapons, or with faulty protection. Neither should we. The key here is to learn God’s word. Hide it in your heart. Then you can put on God’s armor and be able to stand firm.
As it said in the last paragraph, “We cannot fight the enemy if we don’t know the word of God.” This is a key point to remember, because it’s the secret to defeating and overcoming the power of Satan.
Jesus’ Power over Satan
The Bible says that it was for the very purpose of defeating Satan that the Son of God was manifested or revealed.  And by coming to earth and bringing us His law of love and then dying to take our sins, He overcame the Devil. In fact, before Jesus could begin His ministry, He went into the wilderness and was tempted by Satan.
Mark 1:13 And He was there in the wilderness forty days, tempted by Satan, and was with the wild beasts; and the angels ministered to Him.
Watch it: The Great Temptation
Jesus needed to have this battle with Satan in order to put Satan in his place and to prove to Satan that there was no way that he could have power over Him. There is no scenario where Satan will triumph over Jesus. Jesus will always win. Jesus rules supreme, and His power is stronger than any of the power or attacks that Satan can come up with.
Here is a humorous fictional story that illustrates Jesus’ power over the Enemy.
Listen: Jesus and Satan Compete
Jesus and Satan Compete
Jesus and Satan were having a debate about who was better on the computer. So God said, “I am going to set up a test that will run for two hours, and from those results, I will judge who does the better job.”
So Satan and Jesus sat down at the keyboards and typed away.
They e-mailed with attachments.
They did spreadsheets.
They wrote reports.
They created labels and cards.
They created charts and graphs.
They did some genealogy reports.
They did every job known to man.
Jesus worked with heavenly efficiency and Satan was faster than hell.
Then, ten minutes before their time was up, lightning suddenly flashed across the sky, thunder rolled, rain poured, and, of course, the power went off.
Satan stared at his blank screen and screamed every curse word known in the underworld.
Jesus just sighed.
Finally the electricity came back on, and each of them restarted their computers.
Satan started searching frantically, screaming:
“It's gone! It's all GONE! I lost everything when the power went out!"
Meanwhile, Jesus quietly started printing out all of His files from the past two hours of work.
Satan observed this and became irate.
“Wait!” he screamed. “That's not fair! He cheated! How come He has all His work and I don't have any?”
God just shrugged and said, “Jesus saves!”
Our Authority over Satan
You’re not strong enough to fight the Devil on your own, but through the power that Jesus gives us, you have more than enough authority and power over Satan. Since the Word is Jesus, the Word is what Satan fears the most, because the Word exposes and confounds him. It freaks him out so much that it makes him want to get away from you as fast as he can.
Another way to rebuke and bind Satan and his power is by calling on the name of Jesus. Just as Jesus rebuked Satan and commanded him to leave him in the Great Temptation, so can you do the same by using the authoritative and powerful name of Jesus.
Philippians 2:9-10 Therefore God also has highly exalted Him and given Him the name which is above every name, that at the name of Jesus every knee should bow, of those in heaven, and of those on earth, and of those under the earth
When Jesus was with His disciples, He gave them power to cast out devils:
Luke 9:1 Then He called His twelve disciples together and gave them power and authority over all demons, and to cure diseases.
And this power is given to all of those who believe in the name of Jesus:
Mark 16:17 These signs will follow those who believe: In My name they will cast out demons. …
Jesus said, "My sheep hear My voice, and I know them, and they follow Me. And I give them eternal life, and they shall never perish; neither shall anyone snatch them out of My hand."  When we receive Jesus into our hearts, we are His and the Devil cannot take us back, no matter how hard he tries.
But this doesn’t mean that we cannot get into trouble if we are careless or disobedient to what Jesus tells us, and not interested in obeying His admonitions. The Bible warns us to:
The butterfly and the sparrow
A woman told me she was once awakened by a very strange noise of pecking, or something of the kind. When she got up, she saw a butterfly flying back and forth inside the window pane in a great fright, and outside a sparrow pecking and trying to get in. The butterfly did not see the glass, and expected every minute to be caught, and the sparrow did not see the glass, and expected every minute to get the butterfly. Yet all the while that butterfly was as safe as if it had been millions of miles away, because of the glass between it and the sparrow. So it is with a Christian. Satan cannot touch the soul that has the Lord Jesus Christ between itself and him.
On the Winning Side
Though the Devil’s power is great, God’s power is far greater! And in reality, the Devil can’t have any power over your mind or heart unless you let him. If you choose to let God’s light into your life, the darkness will be forced to retreat.
The Devil may continue to fight you, but he can never defeat you if you call on Jesus’ help. In fact, the Devil’s attacks can cause you to grow even stronger spiritually every time you fight him back. As the famous quote from Edmund Burke says, “Our antagonist is our helper.” How true that is. The Devil’s attempts to discourage us, to frustrate our efforts, or to cause us to fear can actually strengthen our resolve to take a stand against him.
Watch it: I Choose to Stand
Ulysses S. Grant said, “The art of war is simple enough. Find out where your enemy is. Get at him as soon as you can. Strike at him as hard as you can and as often as you can, and keep moving on.”
Ask Jesus to help you make your personal stand against any of the Devil’s attacks in your life. And then, keep moving on!
 Ezekiel 28:15
 Ezekiel 28:17
 Genesis 3
 1 John 4:1
 Galatians 5:22-23
 Hebrews 12:1
 Psalm 34:7
 Psalm 91:11
 1 Timothy 6:12
 1 John 3:8
 John 10:27-28