What Is the Role of Unclean Spirits in Humanity?

In the Old Testament, lepers were considered unclean and had to go through certain rituals to become clean if they were healed. In the New Testament, Jesus cast out unclean spirits. Do unclean spirits still operate in the lives of people today? How can we find freedom from all uncleanness? Jesus came to set the captives free. He came to cleanse us from all iniquity and all sin and all uncleanness.