In the Roman Catholic tradition, Saint Michael has four responsibilities:
The story goes that the Prayer to St. Michael was written by Pope Leo XIII after he had a prophetic vision when one day, after celebrating Mass, while conferring with his cardinals, he fell to the floor in a faint. When no pulse was detected, the cardinals called for a doctor, fearing that the Holy Father was dead. Suddenly, Pope Leo awoke and said, "What a horrible picture I was permitted to see!" He went on to relate that, in his vision, when God gave Satan the choice of one century in which he could do his worst against the Church, Satan chose the twentieth century. This bothered the Holy Father to such an extent that he wrote the prayer to St. Michael the Archangel: "St. Michael the Archangel, defend us in battle! Be our protection against the wickedness and snares of the devil. May God rebuke him, we humbly pray, and do thou, O Prince of the heavenly host, by the power of God, thrust into Hell Satan and all the other evil spirits who roam about the world seeking the ruin of souls." Pope Leo then ordered that this prayer be said at the conclusion of every Mass from 1886 forward. This tradition continued until Pope Paul VI issued the Novus Ordo of the Mass in 1968 wherein the prayer to St. Michael and the reading of the "last gospel at the end of the Mass were suppressed.
St. Michael is a prominent figure in the Rite of Exorcism, particularly in driving out demonic infestations of places, when the priest prays: "Most glorious Prince of the Heavenly Army, Holy Michael the Archangel, defend us in battle against the princes and powers and rulers of darkness in this world, against the spiritual iniquities of those former angels. Come to the help of man whom God made in his own image and whom he bought from the tyranny of Satan at a great price. The Church venerates you as her custodian and patron. The Lord confided to your care all the souls of those redeemed, so that you would lead them to happiness in Heaven. Pray to the God of peace that he crush Satan under our feet; so that Satan no longer be able to hold men captive and thus injure the Church. Offer our prayers to the Most High God, so that His mercies be given us soon. Make captive that Animal, that Ancient serpent, which is enemy and Evil Spirit, and reduce it to everlasting nothingness, so that it no longer seduce the nations."
The following prayer is the Original Prayer to St. Michael the Archangel:
O Glorious Prince of the heavenly host, St. Michael the Archangel, defend us in the battle and in the terrible warfare that we are waging against the principalities and powers, against the rulers of this world of darkness, against the evil spirits. Come to the aid of man, whom Almighty God created immortal, made in His own image and likeness, and redeemed at a great price from the tyranny of Satan.
Fight this day the battle of the Lord, together with the holy angels, as already thou hast fought the leader of the proud angels, Lucifer, and his apostate host, who were powerless to resist thee, nor was there place for them any longer in Heaven. That cruel, ancient serpent, who is called the devil or Satan who seduces the whole world, was cast into the abyss with his angels. Behold, this primeval enemy and slayer of men has taken courage. Transformed into an angel of light, he wanders about with all the multitude of wicked spirits, invading the earth in order to blot out the name of God and of His Christ, to seize upon, slay and cast into eternal perdition souls destined for the crown of eternal glory. This wicked dragon pours out, as a most impure flood, the venom of his malice on men of depraved mind and corrupt heart, the spirit of lying, of impiety, of blasphemy, and the pestilent breath of impurity, and of every vice and iniquity.
These most crafty enemies have filled and inebriated with gall and bitterness the Church, the spouse of the immaculate Lamb, and have laid impious hands on her most sacred possessions. In the Holy Place itself, where the See of Holy Peter and the Chair of Truth has been set up as the light of the world, they have raised the throne of their abominable impiety, with the iniquitous design that when the Pastor has been struck, the sheep may be.
Arise then, O invincible Prince, bring help against the attacks of the lost spirits to the people of God, and give them the victory. They venerate thee as their protector and patron; in thee holy Church glories as her defense against the malicious power of hell; to thee has God entrusted the souls of men to be established in heavenly beatitude. Oh, pray to the God of peace that He may put Satan under our feet, so far conquered that he may no longer be able to hold men in captivity and harm the Church. Offer our prayers in the sight of the Most High, so that they may quickly find mercy in the sight of the Lord; and vanquishing the dragon, the ancient serpent, who is the devil and Satan, do thou again make him captive in the abyss, that he may no longer seduce the nations.
Exorcist: Behold the Cross of the
Lord; be scattered ye hostile powers.
All: The Lion of the tribe of Judah has conquered the root of David.
Exorcist: Let Thy mercies be upon
us, O Lord.
All: As we have hoped in Thee.
Exorcist: O Lord, hear my
All: And let my cry come unto Thee.
Exorcist: Let us pray...
O God, the Father of our Lord Jesus Christ, we call upon Thy holy Name, and as supplicants, we implore Thy clemency, that by the intercession of Mary, ever Virgin Immaculate and our Mother, and of the glorious St. Michael the Archangel, Thou wouldst deign to help us against Satan and all the other unclean spirits who wander about the world for the injury of the human race and the ruin of souls.