From The Liturgical Year:
In the sixteenth century Satan made a formidable attack upon the Holy City, by means of a man who, like himself, had fallen from the height of heaven, a man prevented in early years by the choice graces which lead to perfection, yet unable in an evil day to resist the spirit of revolt. As Lucifer aimed at being equal to God, Luther set himself up against the Vicar of God, on the mountain of the covenant; and soon, falling from abyss to abyss, he drew after him the third part of the stars of the firmament of Holy Church. How terrible is that mysterious law whereby the fallen creature, be he man or angel, is allowed to keep the same ruling power for evil which he would otherwise have exercised for good. But the designs of eternal Wisdom are never frustrated: against the misused liberty of the angel or man is set up the other merciful law of substitution, by which St. Michael was the first to benefit.
The development of Ignatius' vocation to holiness followed step by step the defection of Luther.
Ad Maiorem Dei Gloriam!
To the Greater Glory of God!
St. Ignatius of Loyola, pray for us!