For there is also such a thing as a natural zeal for the kingdom of God. The fact that our aim is supernatural does not by itself imply that our attitude is supernatural, too. For one thing, a kind of natural enthusiasm about the kingdom of God is sometimes to be met with, which is likely to flare up impetuously in certain moments but will not stand any hard test. It is deficient in constancy; whenever it encounters defeat or entails the necessity of a heavy personal sacrifice, it is apt to dwindle away. It lacks both ultimate earnestness and sterling solidity.

This kind of zeal is not rare in converts, some of whom have no sooner embraced the Faith than they are busy forming grand projects about extending the kingdom of God. Such short-lived fits of pious zeal, as contrasted with that fire which Our Lord came down to kindle on earth, are also recognizable by the fact that they are devoid of the virtue of discretion. These enthusiasts forget that no one is qualified to labor fruitfully in the vineyard of the Lord who is not also ready to drink the chalice; they have not pondered the parable of the man who wanted to build a tower.

Aggressive, destructive natural zeal for God

Apart from that, however, we know examples of a deep and persevering zeal for the kingdom of God which is still essentially on the natural level. There have been ardent fighters for the cause of God, enduring heavy sacrifices for the kingdom of God and continuing the struggle in the midst of all adversities, yet doing so in a mood of natural pugnacity, in a hard and rigid attitude—men who have failed to grasp the parable of the wheat and the chaff.

Think, for example, of the tragic figure of Pope Paul IV (Caraffa), who was burning with zeal for the house of God, who led a life of austere poverty amidst an environment reeking with worldliness, who would not have hesitated a moment to give his life for the reform of the Church, and yet, whose pontificate was to be so unsuccessful owing to his fanaticism, his asperity, and his lack of trust, that on his death bed he declared it to have been the most unfortunate since St. Peter’s. A world’s distance separates his ethos from that of his gentle, patient fellow friar, St. Cajetan.

Paul IV’s zeal was of the kind that is not anointed with the holy oil of patience; that is not transfigured by discretio; that is apt to degenerate into an angry zealotry devoid of all kindness and trustfulness, and to dash forward with an impetuous fury stemming entirely from the natural man.