When a man says: "Lord Jesus Christ, have mercy on me," do you know what happens? It brings energy, it brings the Grace of the Holy Spirit puts it in action. He orders this "fire" of Divine Grace, to be worked throughout the earth. And how is this done? It brings joy to the angels, and brings sadness and enflames the demons. It is a further hell for the demons.
With every "Lord Jesus Christ, have mercy on me," it is like casting an atomic bomb in the heart of the devil (and because of this, [the devil] fervently puts up roadblocks) and it will be heard unto the ages of ages, not because we ourselves have this Grace, but because the name of Jesus Christ itself carries this energy and Grace and has so much power, as much power and Grace that His Godhead has!
For this Grace to be energized in essence in ourselves, we must have the following presuppositions:
A) frequent sacramental life
B) to have been forgiven by all men,
C) to proceed through life with purity in body and soul,
D) to have a spiritual guide, and,
E) to have an order and daily program of spiritual duties in the realm of silence and compunction.
-Elder Ephraim of St Andrew Skete, Mount Athos