So we must mention Demon-possession. This can be sought deliberately. 1 Kings 18. Various voodoo rites. Possession must not be confused with mental illness.
Scripture carefully distinguishes the two.
All these are entrances into the spirit world, and are forbidden by God. Have nothing to do with false religions, for heathen worship is the worship of demons. Do battle with evil in ALL its forms, using the Word of God as a defensive and offensive weapon. The alternatives are the Holy Spirit or an evil spirit. So, as a believer do not be over awed by demonic forces, or fear that you may be indwelt or possessed yourself.