If you take a closer look at the specific work of demons, you realize that a lot of the of the devil’s attack is dedicated on corrupting our minds. 2 Corinthians 10:4 tells us,
For the weapons of our warfare are not of the flesh but have divine power to destroy strongholds. (ESV)
The word Stronghold here is the Greek word ochúrōma; meaning “To fortify, a stronghold, fortification or fortress. Used metaphorically of any strong points or arguments in which one trusts.
These fortresses were enormous walls designed to keep the people in within the walls and, to keep people from the outside from coming in. When our belief system is corrupted or contrary to God’s Word, it becomes a stronghold and, a stronghold will directly affect our worldview.
Strongholds are a direct attack on the soul designed to corrupt the way we think and our decision-making. As the result of our corrupt way of thinking and bad decisions, these strongholds will leave us to deal with adverse emotions.
The Bible tells us that we are what we think (Proverbs 23:7). A stronghold will define who we are. To bring about changes in our lives, we must change how we think. Dealing with strongholds cannot be fixed with a quit prayer of deliverance. Deliverance is needed to cast those demons out. However, if the person is not confronted with the error of his/her thinking and, is presented with sound doctrine; demons will continue to possess that area of his/her life over and over.
Examples of strongholds are mindset that offer justifications of sins; they put everything under the umbrella that those are issues of the flesh. They do not struggle with the flesh; they surrender to the flesh. They do not live in the Spirit; they live their lives according to their flesh. A stronghold keeps a person from believing in the power of God to make them free.
Those fortresses can be cultural, part of the iniquity of the family, the way they were raise, bad doctrine, etc. They believe and trust God in other areas but are unable to change certain aspects of their worldview. These folks need deliverance, discipleship and to renew our minds! The Apostle Paul tell us,
Do not be conformed to this world, but be transformed by the renewal of your mind, that by testing you may discern what is the will of God, what is good and acceptable and perfect. Romans 12:2 (ESV)
God desires to transform us and, to do so, we must renew our minds and not be conform to the culture of this world. Those strongholds will keep a person from the ability to discern God’s good, acceptable, and perfect will for our lives.
 Spiros Zodhiates, The Complete Word Study Dictionary: New Testament (Chattanooga, TN: AMG Publishers, 2000).