Ephesians 2:2 NKJV

in which you once walked according to the course of this world, according to the prince of the power of the air, the spirit who now works in the sons of disobedience,

All people, saved or unsaved interact with the unseen world. Paul told the Ephesian church that there was an evil spirit at work in the sons of disobedience. It is important for us to realize that sinners are unaware most of the time that their actions are influenced by the unseen realm. Isn't it interesting how people's behavior changes after they exit the kingdom of darkness? It is because they come out from under the influence of demonic forces in the unseen realm. As believers in Christ, we must be careful not to deal with evil spirits who are attacking us through human bodies as if we are dealing with physical beings. We attack the spirits in the spirit realm with spiritual weapons, while loving the human being who is being used by devils, many times unaware. It works the same way for Christians who allow the forces of darkness to influence their behavior. We must forgive them, pray for them and forbid the devil to use them against us or vice versa.