'Spirits' in the Bible

When evening came, they brought to Him many who were under the power of demons; and He cast out the evil spirits with a word, and restored to health all who were sick [exhibiting His authority as Messiah],

Jesus summoned His twelve disciples and gave them authority and power over unclean spirits, to cast them out, and to heal every kind of disease and every kind of sickness.

Then it goes and brings with it seven other spirits more wicked than itself, and they go in and make their home there. And the last condition of that man becomes worse than the first. So will it also be with this wicked generation.”