St. John Chrysostom taught his people how to use this effective spiritual weapon.
An Early Church Father best known for his preaching and profound spiritual writing, St. John Chrysostom was also well aware of the spiritual battle that is being waged all around us.
He taught his people a simple habit in his commentary on the Gospel of John that he believed would prevent any evil presence to enter a person.
Chrysostom examines the fourth chapter of John and starts out with an exhortation to his listeners to understand the scriptures and not simply own a pretty version of it.
I do not hear any one glory that he knows the contents [of scripture], but that he has a book written in letters of gold. And what gain, tell me, is this? The Scriptures were not given us for this only, that we might have them in books, but that we might engrave them on our hearts.
He sees this not only as necessary for the spiritual life, but as a strong defense against the Evil One.
I desire that from those books you convey the letters and sense into your understanding, that so it may be purified when it receives the meaning of the writing. For if the devil will not dare to approach a house where a Gospel is lying, much less will any evil spirit, or any sinful nature, ever touch or enter a soul which bears about with it such sentiments as it contains. Sanctify then your soul, sanctify your body, by having these ever in your heart, and on your tongue. For if foul speech defiles and invites devils, it is clear that spiritual reading sanctifies and draws down the grace of the Spirit.
In other words, St. John Chrysostom believes that a soul who truly abides by the words of Scripture and keeps them always in his heart and lips will be virtually impervious to satanic attacks.
This is essentially what St. Paul says in his letter to the Ephesians, “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 … Therefore take the whole armor of God, that you may be able to withstand in the evil day … And take the helmet of salvation, and the sword of the Spirit, which is the word of God” (Ephesians 6:12,13,17).
Chrysostom understood the spiritual realm clearly and knew how to defeat the powers of Satan. His prayers are even used in the exorcism rites of the Orthodox Church.
May the Lord rebuke thee, Satan! — He Who in glory ascended into heaven to His Father, sitting on the right of majesty upon the throne of glory. Devil: May the Lord rebuke thee!
The scriptures are a powerful defense against Satan, but it must reach the depths of our heart. As the author of Hebrews wrote, “For the word of God is living and active, sharper than any two-edged sword, piercing to the division of soul and spirit, of joints and marrow, and discerning the thoughts and intentions of the heart” (Hebrews 4:12).