St. Michael the Archangel, whose name means “one who is like God,” led the army of angels who cast Satan and the rebellious angels into Hell; at the end of time, he will wield the sword of justice to separate the righteous from the evil (cf. Revelation 12:7ff).
St. Michael the Archangel has been invoked for protection on various occasions. In 590, a great plague struck Rome. Pope St. Gregory the Great led a procession through the streets as an act of penance, seeking forgiveness and atoning for sin. At the tomb of Hadrian (now Castle Sant’ Angelo near St. Peter’s Basilica), St. Michael appeared and sheathed his sword, indicating the end of the plague. The Holy Father later built a chapel at the top of the tomb, and to this day, a large statue of St. Michael rests there.
Therefore, in our Catholic tradition, St. Michael has four duties: (1) To continue to wage battle against Satan and the other fallen angels; (2) to save the souls of the faithful from the power of Satan, especially at the hour of death; (3) to protect the People of God, both the Jews of the Old Covenant and the Christians of the New Covenant; and (4) finally to lead the souls of the departed from this life and present them to our Lord for the particular judgment, and at the end of time, for the final judgment.