Observe,
[1.] The devil is an unclean spirit, his nature directly contrary to that of the pure and holy God, and degenerated from what it was at first.[2.] This unclean spirit works in the children of men; in the souls of many, as then in men's bodies.
[3.] It is possible that those who are very much under the power and working of Satan may yet be found in the synagogue, among the worshippers of God.
[4.] Even the devils know and believe that Jesus Christ is the Holy One of God, is sent of God, and is a Holy One."
Matthew Henry