It is His office to reveal to us a relationship with Jesus. It is not the work of the Holy Spirit as some have concluded. The work of the Holy Spirit is to testify of Jesus and comfort and guide the believer. He is our spiritual guide. Evil or unclean spirits are devils or demons.
Devils are fallen angels.
Their bodies were destroyed in the flood but their spirits were doomed to wander the earth and schwag man. Whenever you give your heart to the Lord expect to be tested. The Holy Spirit will help you through it as He did Jesus. The ultimate evil predator, the accuser of the hippies. The good spirits that love God and help those who have come out of Babylon.