Power of the Name Jesus in Prayer

The most common prayer in the Orthodox Tradition is the Jesus Prayer, "Lord Jesus Christ, Son of God, have mercy on me."  Its power comes from the continual repetition of the Lord's name.  Why is this prayer so powerful and important?

In the Old Testament there is a close connection between someone's soul and his name. Knowing one's names indicates a certain control over Him. A change in name reflects a change in a person's life. Like Saul became Paul or a person who is ordained as a priest or monk receives a new name. In the Hebrew tradition, to do a thing in the name of another person, or to call upon his name are acts of potency.  It makes them effectively present.

In the New Testament devils  are cast out and people are healed in the Name of Jesus. When the disciples were sent out to heal and bring peace to the world they returned with joy saying,  "Lord, even the devils are subject unto us through thy name." (Luke 10:17)  And in another time they said "...we say one casting out devils in thy name." (Luke 9:49)
God's name is linked with His Person and invoking His name has a sacramental character.  Repeating it serves as a sign of His presence and action.
John Climacus says,
Flog your enemies with the Name of Jesus, for there is no weapon more powerful in heaven or on earth.
The name must be spoken with sincerity.

In the last days of Jesus' life he said: "Hitherto have ye asked nothing in my name: ask, and ye shall receive, and your joy may be full... Verily, verily, I say unto you, Whatsoever ye shall ask the Father in my name, he will give it you." (John16:24, 23)

Archimandrite Sophrony says,
"The Name Jesus as knowledge, as 'energy' of God in relation to the world and as His proper Name, is ontologically bound up with Him.  It is spiritual reality. Its sound can merge with its reality but not necessarily so.  As a name it was given to many mortal men but when we pray we utter it with another content, another "frame" of spirit.  For us it is the bridge between us and  Him.  It is the canal along which the streams of divine strength flow to us.  As Proceeding from the Holy God it is holy and it hallows us by its invocation.  With this Name and through it prayer acquires a certain tangibleness: it unites us with God.  In it , this Name, God is present like a scent-gflask full of fragrance.  through it, the Celestial One can be sensed imminently.  As divine energy it proceeds from the Substance of Divinity and is divine itself." (Archimandrite Sophrony, On Prayer, p. 133-134)

All our divine worship is based on invocation of the divine Names. They are said in true confession of faith and in a state of divine reverence and awe.

Saint Ignatius Brianchaninov writes,
"By the power of the name of Jesus the mind is freed from doubt, indecision and hesitation, the will is strengthened and correctness is given to zeal and other properties of the soul.  Then only thoughts and feelings pleasing to God, thoughts and feelings belonging to depraved human nature, only such thoughts and feelings are allowed to remain in the soul  there is no place then for other thoughts and feelings, "for God will save Sion, and the cities of judea shall be builded; and they shall dwell therin and inherit it.  And the seed of Thy servants shall possess it, and they that love thy name shall dwell therein" (Ps 68:40-41) In the name of the Lord Jesus quickening is given to the soul deadened by sin.  the Lord Jesus Christ is life...." (On the Prayer of Jesus, p. 25-26)

John Chrysostom tells us,
Continue constantly in the name of the Lord Jesus, that the heart may swallow the Lord and th Lord the heart, and that these two may be one... (On the Prayer of Jesus, p. 30)