Jesus describes a man as being a HOUSE for evil spirits (Matthew 12:43-45).  More specifically, man has three parts: body, soul (mind, will, and emotions), and spirit (I Thes. 5:23). 
Evil spirits may take up resident in any or all of these three parts: [1] In the body = Matt. 12:22,   [2] In the soul = (mind, will, and emotions) Mark 5:1-15,and  [3] In the spirit = John 13:27.

Even a Christian may allow evil spirits to enter his body or soul (Matt. 18:21-35, Acts 5:3).  Note, only the spirit of a Christian remains exempt from demonic occupation in that his spirit is in eternal union with the Holy Spirit (I Cor. 6:17-20), II Cor. 6:16).   See also Acts 8:23.)

1. The mind of a man is like a TV screen that pictures various thoughts.
2. Thoughts come from different sources: a. From God.  b. From physical stimuli (the five senses). c. From self (memory & imagination). d. From the powers of darkness (evil spirits).
3. Man, unlike all other earthly creatures, was given a conscience by which he can judge the purity of thoughts.  (Rom. 2:14-15).
4. Man was also given the power of his will to choose which thoughts to entertain or reject.
5. When one chooses (by the will) to entertain a specific evil thought, then he leaves his door (the will) open for an evil spirit to enter.
CONCLUSION:  The door is the WILL of man.

Evil spirits crouch like wild animals at the door waiting for an opening to enter (Gen. 4:7).  Again, the door is generally considered the will of man.

If you have allowed evil spirits to enter into you house, then you should also know that you have no power of your own to overcome them.  (Acts 19:15-16).  You need the STRONGER POWER of the Spirit of Jesus in your life. (Luke 11:22).
You may receive this stronger power by praying:
1. I confess to you Jesus that I have sinned.
2. I realized that the penalty for sin is death (in the spirit-man).
3. I believe that you, Jesus, died for all my sins and arose again.
4. I give my life to you, Jesus, letting you become my LORD and SAVIOUR.
5. I ask you to come now and live inside of me by your Spirit.
Rom. 3:10, 3:23, 5:12, 6:23, 5:8, Isa. 53:6, Rom. 10:9-10, Phil. 2:9-11, Ezek. 36:26-27.
REMEMBER:  A vacuum is an invitation for evil spirits.  Matt. 12:43-45.

"For this purpose, the Son of God (Jesus) was manifested, that He might destroy the works of the devil." I John 3:18.
Jesus DEMONSTRATED his own power and authority over evil spirits:
1. By casting them out of people that he met. "They brought unto him many that were possessed with devils: and he (Jesus) cast out the spirits with his word." Mark 8:16.
2. By overcoming Satan in his death and resurrection. "And having spoiled principalities and powers (of darkness), he made a shew of them openly, triumphing over them (evil spirits) in it."  Colossians 2:15.
3. By giving the same power and authority to Believers to bind and cast out evil spirits.  "In my name shall they cast out devils."  Mark. 16:17.

1. Destroy by fire all physical objects in you possession associated with the occult or false religions.  Deut. 7:25-26, Acts 19:13-19.  Some examples are books, magazines, records, CDs, tapes, videos, statues, art objects, charms and other objects of worship.
2. Destroy all personal possessions of drugs, alcohol, and pornography.  James 1:14-15.
3. Confess to God the specific sins of your forefathers.  Lev. 26:40.
4. Confess to God all known sins in your own life asking for His forgiveness.
5. Tell God that you are willing to forgive everyone who has offended you and hurt you.  Then ask God also to forgive them.  Matt. 6:12, 18:22-35, Luke 23:34, Acts 7:59.
6. With God's help be willing to repent of (turn from) all habitual sins.  Acts 3:19.

7. NOW PRAY: "In the name and blood of Jesus, I break all curses that have been placed upon me and my house.  I bind and command every evil spirit to leave me and not to come back."  Sometimes it is necessary to name each of the curses and each of the evil spirits.  Rev. 12:11, Mark 11:22-23, Matt. 18:18, Acts 16:18, Mark 5:8-9.
8. Expect the curses to be broken and the spirits to leave.  Gal. 3:13, James 4:17, Acts 8:6-8.
9. Continue to resist your enemy until you experience deliverance in your life.  Dan. 10:11-13.
10. Praise the name of Jesus.  PRAISE is a mighty weapon to the Believer.  Psa. 149:6-9.
*** If you need someone to  help you in deliverance, counseling is available.

You are able by the grace of God (His will and power working in you) to overcome future attacks of the enemy.  Eph. 4:27, I Cor. 10:13, Phil. 2:13.   You CAN close the door (II Cor. 2:11) to the enemy by taking the following steps:
1. Understand that nothing can separate you from the love of God.  Rom. 8:35-39, John 10:28.
2. Be baptized (immersed) considering yourself dead to sin, but alive unto God.  Rom. 6:3-15.
3. Cast all your cares upon Jesus because he cares for you.  I Peter 5:7-9.
4. Put on all the armor of God and pray daily.  Eph. 6:10-18.
5. Reject wrong thoughts and run from all temptations to sin.  II Cor. 10:4-5, II Tim. 2:22.

You should not only close the door to the enemy, but you should, as a Believer, also open the door to your soul to JESUS.  Jesus is now knocking at the door of your soul (mind, will, and emotions) desiring to enter.  Rev. 3:20.
1. Be baptized in and filled with the Holy Spirit.  Acts 1:8, Luke 11:1-13, Eph. 5:18. 2. Yield all personal rights that you may have to Jesus letting Him take control over all areas of your life.  Rom. 12:1-2, Rev. 3:20.
3. Read, memorize, meditate upon and obey God's Word.  Rev. 1:3, Psa. 119:11, Josh. 1:8, James 1:21-22.
4. Join a local church and submit yourself to the authority of the Pastor and Elders.  Heb. 10:25, 13:17.
5. REMEMBER: Greater is the Holy Spirit in you than the devil and his spirits in the world.  I John 4:4.