Both in the Old and the New Testament, the holy Archangel Michael is called the “guardian angel of the people of God”. He is also honoured as the “Herald of the General Judgment” and the “Guardian of Paradise”. It is his office to lead all the elect into the Kingdom of Eternal Glory.
Defender and leader of God’s people in Paradise
The world’s history is replete with instances of St Michael’s solicitude for the children of men during the time of their earthly pilgrimage. He began to fulfil his office as defender and leader of God’s people in the Garden of Paradise. St Ambrose says that God commissioned St Michael to lead Adam into Paradise, to explain to him the purpose of his creation, to guide him and to associate with him in visible form. After the fall of Adam and Eve, this same glorious Archangel stood guard at the gate of Paradise with flaming sword, “to keep the way of the tree of life” (Gen 3:24).
The Fathers of the Church tell us that even though in many instances the name of St Michael is not mentioned in Holy Scripture, when reference is made to the services of an angel, we may confidently believe that it was either St Michael himself who rendered assistance, or his angelic subjects, who did so at his command.
They speculate that it may have been St Michael who warned Noe [Noah] of the coming flood, and that it was through St Michael that Abraham was named the father of the chosen people and received that wonderful promise which Holy Church has immortalised in her prayers for the dead: “May the holy standard-bearer, Michael, introduce them into that holy light which thou didst promise of old to Abraham and his descendants.”
The Angel who appeared to Moses in the burning bush (Ex 3:2) was St Michael, according to the teaching of St Gregory Nazianzen. It was this mighty Angel who performed the wonders which took place at the departure of the Israelites from Egypt, and through whom God gave the Ten Commandments to the Israelites on Mount Sinai. Likewise, the Angel who routed the army of Sennacherib (4  Kings 19:35) was the holy Archangel Michael.
After the death of Moses, according to an ancient Jewish tradition to which St Jude refers to in his Epistle (Jude 1:9), St Michael concealed the tomb of Moses from the people, and also from Satan, who wished to disclose it to the Israelites to seduce them thereby to the sin of false worship.
God revealed to St Michael the designs of His justice and mercy regarding His chosen people. Of this the prophecies of Daniel and Zacharias bear witness. Finally, it was this great celestial prince who aided the Israelites and rendered the army of Judas Macchabeus victorious over their enemies.
(Even to this day the Jews invoke the holy Archangel Michael as the principal defender of the Synagogue and their protector against enemies. On the Feast of the Atonement they conclude their prayers with this beautiful invocation: “Michael, Prince of Mercy, pray for Israel, that it may reign in Heaven, in that light which streams forth from the face of the King who sits upon the throne of mercy.”)
Protector of the Church
Just as the chosen people of the Old Law were marvellously protected by St Michael, so we may believe that this same prince of Heaven protects the Church of God even more wonderfully. Under the New Law, as under the Old, St Michael is the “Vicar of the Most High and the Prince of His people,” ever prepared to render assistance. The Fathers of the Church are of one mind in teaching that St Michael is the guardian angel and the protector of the Catholic Church.
Time and again, in centuries past, St Michael came to the rescue when dreadful wars and persecutions threatened to destroy Christianity. He it was who, at the command of Mary, Queen of Angels, came to the assistance of Constantine the Great in the fourth century and helped his forces to gain a brilliant victory over the pagan Emperor Maxentius. The Archangel himself revealed his identity in this instance. Appearing to Constantine after the completion of a beautiful church, which the latter had erected in his honour in gratitude, he said: “I am Michael, the chief of the angelic legions of the Lord of hosts, the protector of the Christian religion, who while you were battling against godless tyrants, placed the weapons in your hands.” This famous edifice, generally known as the Michaelion, has been the scene of many miracles wrought through the great Archangel.
Later, St Michael proved himself a powerful protector against invasion. The Greek Emperor Justinian erected six churches in his honour, in grateful recognition of his assistance. St Joan of Arc, the Maid of Orleans, who in the fifteenth century saved France, ascribed her vocation and her victories to St Michael. Three times he appeared to her and informed her that she was called to deliver her country. In the sixteenth century, when it seemed that the Turks (Muslims fighting under the Turkish sultan) would conquer all Europe, St Michael at the command of the Blessed Virgin again championed the cause of the Christian (Catholic) Faith, and a glorious victory was gained over the infidels at the Battle of Lepanto.
Thus has St Michael proved himself a valiant warrior for the honour of God, both in Heaven and on earth. And he still wages incessant war with the archfiend Satan in the great Kingdom of God on earth, the Church.
Victorious St Michael
Blessed Anne Catherine Emmerich was reputed to have had visions of the past and future combats of the Church. Repeatedly she saw St Michael, in the form of a warrior, standing above the Church, replacing his bloodstained sword in its scabbard as a sign of victory. She was also shown how, in the present-day struggles of the Church, St Michael would bring about a most glorious victory. This thought should be consoling to all faithful Christians who view with alarm the many shafts of persecution now being directed against the Church.
Pope Leo XIII, realising by divine enlightenment the present and future struggles of the Church against the powers of Hell, felt convinced that through the intervention of St Michael, Hell would be conquered and the Church restored to peace and liberty. He therefore composed a prayer in honour of this warrior Archangel and ordered it to be recited daily after low Mass in all the churches throughout the Christian world.
It is said that one day, having celebrated the Holy Sacrifice, the aged Pontiff was in conference with the Cardinals. Suddenly, he sank to the floor in a deep swoon. Physicians who hastened to his side feared that he had already expired, for they could find no trace of his pulse. However, after a short interval the Holy Father rallied and, opening his eyes, exclaimed with great emotion: “Oh, what a horrible picture I was permitted to see!” He had been shown in spirit the tremendous activities of the evil spirits and their ravings against the Church. But in the midst of this vision of horror, he had also beheld consoling visions of the glorious Archangel Michael, who had appeared and cast Satan and his legions back into the abyss of Hell. Soon afterwards, he composed the well-known prayer: “St Michael, the Archangel, defend us in the battle. Be our safeguard against the wickedness and the snares of the devil. May God rebuke him, we humbly pray…”
The Church has special need of St Michael’s powerful protection in our times. On all sides she is assailed by strong and bitter enemies. In one country after another, religious persecution rises to an ever higher pitch of hatred and insolence. The terrible crimes which have been committed in recent times, and are still being committed against the Church, both in her sanctuaries and against her members, surely are instigated by the devil. No human mind could be base enough to conceive and put them into execution.
The gates of Hell shall never prevail
We know that the gates of Hell shall never prevail against the Church, for our Lord has promised to be with her till the End of Time, but we must do our part in defending her cause. God might have cast the rebel down into Hell by a single act of His Will, but he chose rather to send against them His armies of loyal spirits under the leadership of the great St Michael. So too, in the present critical times, He could confound the enemies of the Church by merely willing to do so. But He wills, rather, that we should cooperate in her defence under the leadership of the Great Captain of the heavenly hosts.
– From: ‘Neath St Michael’s Shield, Fifth Edition, 1962