The power of your thoughts - Where many strongholds begin
The enemy loves to put thoughts into the believer's mind. Those thoughts (if meditated on), produce strongholds, which produces feelings, which lands you into bondage... all because you listened to the devil more then your heavenly Father! I am going to use a common stronghold here in this teaching as an example... an incorrect perception of who you are in Christ. There are many other strongholds out there, but this teaching will give you a general idea of how many strongholds are formed.
How it works
Two voices are speaking: Satan likes to come along and tell you, "Look at that sin you did 5 years ago! That was so bad! You are such a failure!" But Jesus, through God's Word, tries to tell you that if you turn to Him, you will be forgiven (1 John 1:9), and your past will be forgotten: Isaiah 43:25, "I, even I, am he that blotteth out thy transgressions for mine own sake, and will not remember thy sins."
You are faced with a choice: You can either listen to Satan's lie that you are a failure, or you can listen to God's Word that tells you that your past has been washed away and you are a new creature in Christ! 2 Cor 5:17, "Therefore if any man be in Christ, he is a new creature: old things are passed away; behold, all things are become new."
Whichever voice you listen to will crowd the other one out: If you have two dogs that fight all the time, and you can only afford to feed one of them, how do you know which one will win? The one you feed! The same is true in the spiritual realm. The more you listen to Satan's lies and deception, the more he will build strongholds in your mind, and the more strongholds that go up, the harder it will be to hear God's voice. The other side of the coin is true too... the more you feast yourself on the truth in God's Word, the more it tears down strongholds and makes it harder for the enemy's voice to penetrate your system.
If you listen to Satan's lies that you are a failure, he will continue to feed you that lie, and it will grow into a stronghold (a lie that is believed, or an incorrect thinking pattern). Your feelings are quite often a direct result of your thoughts. If you think you are a failure, you will feel like one.
If you listen to your heaven Father, who is speaking truth to you through His Word, you will begin to tear down the strongholds in your life. When you meditate on the truth in God's Word, it will become part of you, and before long, you will be feeling different, simply because you are exchanging lies of the devil for the truth in God's Word. When you believe that your sins are forgiven, you can then allow your conscience to be cleansed from dead works by the blood of Jesus: Hebrews 9:14, "How much more shall the blood of Christ, who through the eternal Spirit offered himself without spot to God, purge your conscience from dead works to serve the living God?"
A practical example
Let me show you how many believers end up feeling like losers... guilt-ridden by their pasts. It all starts with a simple voice of condemnation from the enemy. Satan, through his network of evil spirits (that's how the devil speaks to people, since Satan can't be everywhere at once), injects thoughts into their mind that remind them of their past and their failures. They begin to listen to his voice and agree with it. They did sin, and they failed. But instead of looking at the solution, which is repentance and the blood of Jesus (which washes away sin), they continue to listen to the enemy who keeps reminding them of their past. As they continue to do this, stronghold(s) are formed. A stronghold is an incorrect thinking pattern based on lies and formed in deception. Once a stronghold is in place, the person naturally thinks of their past instead of focusing on the fact that their past has been forgiven and wiped away. They believe they are a failure instead of believing the truth in God's Word, which tells them that they have been forgiven, washed clean, and even God Himself has chosen to forget their dirty past! So instead of feeling like a child of God who was washed clean in the blood of Jesus, they feel unworthy, guilty and consider them self a loser. What a shame for a child of God to feel that way!
Your thoughts can affect how you feel
When you believe something, it will affect your feelings. When you believe you are a failure, you will feel like one. When you believe you are a forgiven saint, you will feel like one.
The difference between a guilt-ridden Christian and a light-hearted and joyful Christian is often one simple thing... what they are thinking about. Guess who's thinking about the sin, the guilt and the past? Now guess who's thinking about how they have been washed clean and they are a new person in Christ Jesus?
Whatever you keep your mind on (think about often) will affect your whole being. Isaiah 26:3, "Thou wilt keep him in perfect peace, whose mind is stayed on thee: because he trusteth in thee."