There is an imaginary room with an imaginary door and in this room are a group of people who aren't aware that they are in a room at all. Outside the door to this room is a control panel with a microphone connected to a hidden speaker inside the room and In front of this microphone is a scientist who decides to see what would happen if talks into the microphone, he starts by saying hello, and notices that the volume on the speaker inside the room is so low that it's almost imposible for anyone to hear him

he tries again, this time he says hello im outside the door, and notices that some of the people seem to wander to the door, but dont seem aware that he had spoken.Fascinated he tries again...this time he says "Your Hungry" into the microphone,and to his amazement people begin to eat, but not everyone our scientist realises that simply by speaking into the microphone he can put a thought and desire into the minds of the people in the room and the people not aware of what he is doing simply act on what there minds are telling them. His thoughts in essence become their own.

but some people didn't react which led our scientist to conclude that he could put the thought in peoples minds but it was up to them to choose whether or not to listen to him. Fascinated he tries several more suggestions and learns that not only can he put thoughts into the minds of these people, but he can also manipulate them, saying one thing to one half, different things to another and effectively cause many of them to do whatever he wishes.

THE WORLD IS THE ROOM AND THE DEVIL HAS THE MICROPHONE

Of course the above story is just my way of trying to  illustrate this point, but deception is very real thoughts and desires designed to cause you to sin are being hammered at you daily evil is not satisfied simply by telling you that your hungry its suggestions are far worse, It hammers you with feelings,desires and thoughts designed to decieve you and keep you in a state of complete disobedience to God. Ultimately enslaving you throughout your whole life with the end result of you dying in your sin and forever being lost. Recognizing them and turning to Jesus is what you need to do. 

Isn't it amazing how you can be having a fantastic day, everything is going perfect than suddenly a thought comes into your mind  "my wife is cheating on me". She doesn't love me,she's just pretending.. Your at work and suddenly the thought comes everyone is talking about me.. or a memory of something that happened in your past comes and you rehearse it over and over, thinking how much you were mistreated and how unfair it is that so and so did this or so 
and so did that.

You than add an audience and make a big speech saying what you wish you had said than and vow in your mind that you will never forgive them.... You are happily married and a pretty young girl walks by, suddenly you think my wife will never know and you begin to fantasize about the girl.. You keep fantasizing about it, and before you know it you have that affair, your wife finds out and the end result is that she leaves you, your life is destroyed.

Deception and temptation is very real,  Jesus in talking to the people of his day describes the devil as a murderer and the father of Lies 

John 8:39-44

The people said to Jesus, "Abraham is our father!" Jesus replied, "If you were Abraham's children, you would do what Abraham did. Instead, you want to kill me for telling you the truth that God gave me. Abraham never did anything like that. But you are doing exactly what your father does." 

In which they replied...

"Don't accuse us of having someone else as our father!" they said. "We just have one father, and he is God." 

Jesus answered: 

If God were your Father, you would love me, because I came from God and only from him. He sent me. I did not come on my own. Why can't you understand what I am talking about? Can't you stand to hear what I am saying? Your father is the devil, and you do exactly what he wants. He has always been a murderer and a liar. There is nothing truthful about him. He speaks on his own, and everything he says is a lie. Not only is he a liar himself, but he is also the father of all lies. 

Learn to recognize when thoughts to decieve you enter your mind. The bible tells us what to look for.. 

Galatians 5:19-40

The acts of the sinful nature are obvious: sexual immorality, impurity and debauchery; idolatry and witchcraft; hatred, discord, jealousy, fits of rage, selfish ambition, dissensions, factions and envy; drunkenness, orgies, and the like. I warn you, as I did before, that those who live like this will not inherit the kingdom of God. 

1 Pet 5:8,9

Be on your guard and stay awake. Your enemy, the devil, is like a roaring lion, sneaking around to find someone to attack. But you must resist the devil and stay strong in your faith. You know that all over the world the Lord's followers are suffering just as you are.

I took this from another site

Seeds Of Deception by Ralph Mohoney, 

How does the devil roar his way into our daily lives? He does so by way of our thoughts and feelings. He sows seeds of doubt and fear into the ground of our hearts and minds. If he can tempt us to cultivate or nurture these seeds - they will grow into very large weeds. When they do, our Christian life can be greatly weakened, or even destroyed.

There are all kinds of seeds which the devil sows: seeds of doubt, fear, disobedience, greed, lust, jealousy, pride, anger, resentment, self-pity and many more.

He will try to sow the same seed over and over again until some take root and grow. Once the roots grow deep, it's hard to pull the weed out.

The devil will even deceive us into thinking it is a natural part of our life. We then give in and put up with it, even though it may be painful to us - and to others. When we do, the enemy has taken control over that part of our lives, even though he has no authority to do so.

So what do we do? first learn to recognize the thoughts when they come and than once you do fight back...
The worst thing you can do is entertain them, ponder them, consider them, give a hold to satan on your life...

James 4:7
Submit yourselves therefore to God. Resist the devil, and he will flee from you.

Romans 12:21
Do not be overcome by evil, but overcome evil with good.

Ephesians 6:11-12

Put on the full armor of God so that you can take your stand against the devil's schemes. For our struggle is not against flesh and blood, but against the rulers, against the authorities, against the powers of this dark world and against the spiritual forces of evil in the heavenly realms.

If we keep reading the The Full armour of God is stated in Ephesians 6:13-18 is

1. The belt of truth 
2. The breastplate of righteousness
3. Gospel of peace
4. The shield of faith
5. The helmet of salvation
6. And the sword of the Spirit, which is the word of God
7. And pray in the Spirit on all occasions with all kinds of prayers and requests

Ephesians 6:13-18

Therefore put on the full armor of God, so that when the day of evil comes, you may be able to stand your ground, and after you have done everything, to stand. Stand firm then, with the belt of truth buckled around your waist, with the breastplate of righteousness in place, and with your feet fitted with the readiness that comes from the gospel of peace. In addition to all this, take up the shield of faith, with which you can extinguish all the flaming arrows of the evil one. Take and the sword of the Spirit, which is the word of God. And pray in the Spirit on all occasions with all kinds of prayers and requests. With this in mind, be alert and always keep on praying for all the saints

When tempted in the desert Jesus used the word of God to defeat the lies and tempations of satan...

Luke 4:1-8 (KJV)

And Jesus being full of the Holy Ghost returned from Jordan, and was led by the Spirit into the wilderness, 
Being forty days tempted of the devil. And in those days he did eat nothing: and when they were ended, he afterward hungered. 
And the devil said unto him, If thou be the Son of God, command this stone that it be made bread. 
And Jesus answered him, saying, It is written, That man shall not live by bread alone, but by every word of God. 
And the devil, taking him up into an high mountain, shewed unto him all the kingdoms of the world in a moment of time. 
And the devil said unto him, All this power will I give thee, and the glory of them: for that is delivered unto me; and to whomsoever I will I give it. If thou therefore wilt worship me, all shall be thine. 
And Jesus answered and said unto him, Get thee behind me, Satan: for it is written, Thou shalt worship the Lord thy God, and him only shalt thou serve.

What better example of how to defeat evil than the one given by our Lord himself... deception starts in the mind and it is in the mind where you must draw your sword, the sword as we've seen from Ephesians is the word of God, it is the word of God that Jesus used when tempted and it is the word of God that we must use as well..

If a thought enters your mind to cheat on your wife for example, recognize it for what it is, bind it and make it captive to the obedience of Christ. Meaning refuse to think on it, refuse to accept it, refuse to ponder it,than counter it with the TRUTH...the truth is the word of God and the word of God in this example says.. 

Matthew 5:27-28 (KJV)
Ye have heard that it was said by them of old time, Thou shalt not commit adultery But I say unto you, That whosoever looketh on a woman to lust after her hath committed adultery with her already in his heart

If you are about to pray and the thought comes to you that you aren't worthy to pray to God immediately recognize the lie , bind it and speak the truth.. which is that we are made right before God through our Lords sacrifice for us.

2 Corinthians 5:20-21
God made him who had no sin to be sin for us, so that in him we might become the righteousness of God.
 

It is when you accept the thoughts and begin to consider them, imagine yourself in them play it out in your mind that sin takes root..and once it has it's a battle to drive it out, by doing so you give evil a foothold into your life, be wise think what it is that the devil is trying to do to you, and reject it!

Romans 12:2

Do not conform any longer to the pattern of this world, but be transformed by the renewing of your mind. Then you will be able to test and approve what God's will is—his good, pleasing and perfect will

2 Corinthians 10:4-5 (KJV)

For the weapons of our warfare are not carnal, but mighty through God to the pulling down of strong holds;) Casting down imaginations, and every high thing that exalteth itself against the knowledge of God, and bringing into captivity every thought to the obedience of Christ;
 

Satan will do his best to destroy your life, to keep you from God-- To fill you with fear,with doubt, worry...your only defense is truth and truth can only be found in one place the bible. Without it you are like a soldier going to the front lines with one bullet. It is so important that not only you get in the word but that you STAY in the word. Is it easy no.. the victory is ours but only if you choose to use it.