Recall that St. Peter tells us, “Be sober, be watchful. Your adversary the devil prowls around like a roaring lion, seeking some one to devour” (1 Peter 5:8). St. Paul writes: “For we are not contending against flesh and blood, but against the principalities, against the powers, against the world rulers of this present darkness, against the spiritual hosts of wickedness in the heavenly places” (Ephesians 6:12).
The Rosary is a powerful weapon to put the demons to flight and to keep oneself from sin... If you desire peace in your hearts, in your homes, and in your country, assemble each evening to recite the Rosary. Let not even one day pass without saying it, no matter how burdened you may be with many cares and labors.
–Pope Pius XI
–from the book The Rosary: Your Weapon for Spiritual Warfare