We have to stay rooted in the bible to understand what these evil spirits are NOT. They are not spirits or souls from dead people, the bible tells us clearly our soul and spirit goes to Heaven or Hell, nothing in-between. These evil spirits are not "evil energy" or "bad energetic vibes", it's the Devil and his demonic spirits he rules over. We also don't talk to these spirits, we only talk to the Holy Spirit and we are commanded to test spirits to be sure they are from God (1 John 4). Regardless of what these spirits say, if they do not confess Jesus has come in the flesh then it's evil! If they appear as dead relatives then it is the demonic spirits that were in your dead relative(s). These demons could also be from witchcraft that was done before you moved in.
Even Paul in wrested with a demonic spirit oppressing him in 2 Corinthians 12. Hebrews 12:2 tells us to look at Jesus as the author and finisher of our faith, and even Jesus was tempted of the devil in Matthew 4! We even read in 2 Corinthians 10: 3-6 & Ephesians 6: 10-18 that the enemy we are fighting against isn't a person or a chemical imbalance causing depression, it's rulers of darkness, principalities, spiritual wickedness, the Devil and his fallen angels, and our own thoughts that are against God!
The goal of these demonic spirits is to steal, kill, and destroy (John 10:10). They bring sickness, unholy desires, diseases, depression, and so many more terrible things regardless if you're saved. Their goal is to do everything they can to make your life a living hell, but there is a way to over come them! And Jesus has come to free the captives, give back, give life and build up by his Holy Spirit! Freedom from this demonic oppression is obtainable if you've given your life to Christ, been baptized and truly repented!
This path to freedom from these oppressive demons is grounded on the authority God has given us in Luke 10:19 & Mark 16:16-18! We command them to leave in the name of Jesus Christ. God has also given us the bible as a real sword to use against the enemy (Hebrews 4:12). The question is, how to you combine these things to obtain the freedom Jesus promised us? You can click the link here to be taken to a guide to self-deliverance. This works on yourself and can be applied to others as well.