The Soul Versus The Spirit

Many find it hard to believe that a born again believer can have a demonic spirit simply they don't understand the difference between the soul and the spirit of a man. They believe everything is made new the moment a person accepts Jesus (which is true for the man's spirit), but they naturally accept the fact that a person can be born again yet they can still be in bondage to sin (darkness or evil).
The soul and the spirit are not the same

Even though our Bible uses the words soul and spirit interchangeably, there is a very distinct difference that we cannot ignore. These passages in God's Word that make a very clear distinction between the soul and the spirit:
Hebrews 4:12, "For the word of God is quick, and powerful, and sharper than any two-edged sword, piercing even to the dividing asunder of soul and spirit, and of the joints and marrow, and is a discerner of the thoughts and intents of the heart."
1 Thessalonians 5:23, "And the very God of peace sanctify you wholly; and I pray God your whole spirit and soul and body be preserved blameless unto the coming of our Lord Jesus Christ."
So what is the difference between the soul and the spirit?
We are a spirit being, we live in a body and we possess a soul. The real person inside of us is our spirit. Our soul consists of our mind, will and emotions. Our bodies are obviously what we live in while we are here on earth. How did demonic spirits vex and possess (control) people in the Bible? It was through their souls (minds, as in mental illness and insanity), and their bodies (as in the woman who had the spirit of infirmity).
Example of physical (bodily) demonic affliction: Luke 13:11, "And, behold, there was a woman which had a spirit of infirmity eighteen years, and was bowed together, and could in no wise lift up herself."
Example of mental (soul) demonic affliction: Matthew 17:15,18, "Lord, have mercy on my son: for he is lunatic, and sore vexed: for ofttimes he falleth into the fire, and oft into the water... And Jesus rebuked the devil; and he departed out of him: and the child was cured from that very hour."
Our spirits ARE born again!
The moment we accept Christ, our spirits become brand new. We are a completely new person, we are born of God, and we are made alive with God:
2 Corinthians 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."
This is speaking of our spirits, which are instantly made new the moment we accept Christ.
The Bible even tells us that the old man in us has died with Christ, and that we are raised to new life through Christ's resurrection:
Romans 6:2-6, "God forbid. How shall we, that are dead to sin, live any longer therein? Know ye not, that so many of us as were baptized into Jesus Christ were baptized into his death? Therefore we are buried with him by baptism into death: that like as Christ was raised up from the dead by the glory of the Father, even so we also should walk in newness of life. For if we have been planted together in the likeness of his death, we shall be also in the likeness of his resurrection: Knowing this, that our old man is crucified with him (our spirits that were alive to sin), that the body of sin might be destroyed (speaking of the evil in our souls), that henceforth we should not serve sin."
Even though we have died to sin, and been raised to new life through Christ Jesus, our souls (that is, our minds) still need to be transformed and purified by the washing of the Word:
Ephesians 5:26, "That he might sanctify and cleanse it with the washing of water by the word."
Our souls are NOT born again!
The Bible is clear that even though our spirits are born of incorruptible seed, our minds (souls) still need to be purified, that is, cleansed:
1 Peter 1:22-23, "Seeing ye have purified your souls in obeying the truth through the Spirit unto unfeigned love of the brethren, see that ye love one another with a pure heart fervently: Being born again, not of corruptible seed, but of incorruptible, by the word of God, which liveth and abideth forever."
Our spirit is instantly reborn and made new the moment we accept Christ, but the soul is not born again. Our souls are transformed by the renewing of our minds:
Romans 12:2, "And be not conformed to this world: but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect, will of God."
Some closing thoughts
Our spirits are made right with God, and raised to new life the moment we accept Jesus, but our souls (minds) can carry much spiritual grime and dirt over from our past lifestyles. Our souls are transformed by the renewing of our minds and by the washing of the Word, as the Bible makes clear. This is why so many believers can continue to struggle with sin even after accepting Christ. Their souls still contain grime and dirt that needs to be removed and washed clean.
Demonic spirits can also remain in our souls, and must be driven out as Jesus and the early church went about doing. If all a person had to do was accept Jesus and all their unclean spirits departed, then what would be the point in casting demons out of anybody? If all we would had to do was get people saved and their demons would automatically shed, then casting out demons would be sort of pointless, wouldn't it? However, the practice of casting out demons didn't end when Jesus ascended into heaven. It was a popular ministry that was carried right into the early church, and is still in full swing today. After all, before Jesus went to sit at the right hand of the Father, He made it clear that them who believe will be casting out demons!
Mark 16:17, "And these signs shall follow them that believe; In my name shall they cast out devils..."
There is a very real need for the ministry of deliverance. I have seen lives practically flipped upside-down through deliverance! Many tears of joy and freedom are shed, and people walk away never to be the same again!