Allows people to fall…

The Lord sometimes allows people who are devoted to Him to fall into such dreadful vices; and this is in order to prevent them from falling into a still greater sin– pride. Your temptation will pass and you will spend the remaining days of your life in humility. Only do not forget your sin.
–Saint Seraphim of Sarov (1754-1833)

The beginnings of temptation…

Above all, we must be especially alert against the beginnings of temptation, for the enemy is more easily conquered if he is refused admittance to the mind and is met beyond the threshold when he knocks. Someone has said very aptly: “Resist the beginnings; remedies come too late, when by long delay the evil has gained strength.” First, a mere thought comes to mind, then strong imagination, followed by pleasure, evil delight, and consent. Thus, because he is not resisted in the beginning, Satan gains full entry. And the longer a man delays in resisting, so much the weaker does he become each day, while the strength of the enemy grows against him.
–Thomas à Kempis (1380-1471)

The devil dreads…

The devil dreads fasting, prayer, humility, and good works: he is not able even to stop my mouth who speak against him. The illusions of the devil soon vanish, especially if a man arms himself with the Sign of the Cross. The devils tremble at the Sign of the Cross of our Lord, by which He triumphed over and disarmed them.
–Saint Anthony of Egypt (c. 251-356)