3 “The Lord is my helper; I will not fear what man does unto me”. But are men, then, the only enemies that the Church has? What is a man devoted to flesh and blood, save flesh and blood? But the Apostle says, “We wrestle not against flesh and blood, but against,”...he says, “spiritual wickedness in high places;” that is, the devil and his angels; that devil whom elsewhere he calls “the prince of the power of the air.” Hear therefore what follows: “The Lord is my helper: therefore shall I despise mine enemies”. From what class soever my enemies may arise, whether from the number of evil men, or from the number of evil angels; in the Lord's help, unto whom we chant the confession of praise, unto whom we sing Allelujah, they shall be despised.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)