The Holy Apostle Paul assures the Ephesians, "For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places." Here he refers to that vast multitude of demonic hosts that inhabit the air around us, ever striving to corrupt our minds and hearts during the course of this earthly life, while obstructing the course of our path to the Throne of God at that dreadful moment when the soul departs from the body.
Nevertheless, it is evident from today's Gospel reading that the demons are, in a sense, but paper tigers. Though Satan has been given leave, according to the providence of God, to prowl the earth, like a ravening lion seeking whom he may devour, his rule is strictly limited to the time preceding the Final Judgment of God, and even so, it is subject to the supreme authority of Jesus Christ the Pantocrator. And so it is that the demons cry out to our Lord, "What have we to do with Thee, Jesus, thou Son of God? art thou come to torment us before the time?"
And so it is that even the demons are compelled to confess Christ. As St. James writes, "Thou believest that there is one God; thou doest well: the devils also believe, and tremble." So it is that even the demons, while confessing Christ, require His permission to enter the swine, "and behold, the whole herd of swine ran violently down a steep place, and perished in the waters." For truly Satan is a murderer from the beginning, and that very same destruction the demons wrought upon the swine, they would gladly accomplish upon the human race. Fortunately, though, the demons have not been granted the power to destroy a single human life. Through their wicked suggestions, they can surely incline us towards that dark path of destruction that leads to eternal damnation in a hell of our own making... but only if we freely and voluntarily submit ourselves to their authority.
Having been baptized into Christ, we Orthodox Christians have put on Christ, and therefore we have been given, through the Church, the armor of God and the weapons required that we might engage in that spiritual warfare to which we have been called. For while we should never underestimate the powers of evil arrayed against us, and while the demons are indeed fierce adversaries fully capable of striking abject fear into the hearts of the faithful, we must ever keep in mind St. Paul's injunction, "If God is for us, who can be against us?" For indeed, through the power of the most sacred and life-giving Cross, "we are more than conquerors through Him Who loved us:" our Lord, God, and Savior Jesus Christ.