Those who have read The way of a Pilgrim are familiar with the expression 'The Jesus Prayer'. It refers to a short prayer the words of which are: 'Lord Jesus Christ, Son of God, have mercy on me, a sinner,' constantly repeated. The Way of a Pilgrim is the story of a man who wanted to learn to pray constantly (1Thes 5:I7). As the man whose experience is being related is a pilgrim, a great many of his psychological characteristics, and the way in which he learned and applied the prayer, were conditioned by the fact that he lived in a certain way, which makes the book less universally applicable than it could be; and yet it is the best possible introduction to this prayer, which is one of the greatest treasures of the Orthodox Church.
The prayer is profoundly rooted in the spirit of the gospel, and it is not in vain that the great teachers of Orthodoxy have always insisted on the fact that the Jesus Prayer sums up the whole of the gospel. This is why the Jesus Prayer can only be used in its fullest sense if the person who uses it belongs to the gospel, is a member of the Church of Christ.
All the messages of the gospel, and more than the messages, the reality of the gospel, is contained in the name, in the Person of Jesus. If you take the first half of the prayer you will see how it expresses our faith in the Lord: 'Lord Jesus Christ, Son of God.' At the heart we find the name of Jesus; it is the name before whom every knee shall bow (Is 45:3), and when we pronounce it we affirm the historical event of the incarnation. We affirm that God, the Word of God, co-eternal with the father, became man, and that the fullness of the Godhead dwelt in our midst (Col 2:9) bodily in his Person.
To see in the man of Galilee, in the prophet of Israel, the incarnate Word of God, God become man, we must be guided by the spirit, because it is the spirit of God who reveals to us both the incarnation and the lordship of Christ. We call him Christ, and we affirm thereby that in him were fulfilled the prophecies of the Old Testament. To affirm that Jesus is the Christ implies that the whole history of the Old Testament is ours, that we accept it as the truth of God. We call him Son of God, because we know that the Messiah expected by the Jews, the man who was called 'Son of David' by Bartimaeus, is the incarnate Son of God. These words sum up all we know, all we believe about Jesus Christ, from the Old Testament to the New, and from the experience of the Church through the ages. In these few words we make a complete and perfect profession of faith.
But it is not enough to make this profession of faith; it is not enough to believe. The devils also believe and tremble (James 2:I9). Faith is not sufficient to work salvation, it must lead to the right relationship with God; and so, having professed, in its integrity, sharply and clearly, our faith in the Lordship and in the Person, in the historicity and in the divinity of Christ, we put ourselves face to face with Him, in the right state of mind: 'Have mercy on me, a sinner'.