The starting point of Gregory’s theological approach is the fact that Christianity deals not with an ‘unknown God’,[1] not with a silent God, but with the God Who revealed Himself to humanity as an incarnate Word. Therefore the sacrifice of word on the part of the humans is ‘more sacred and pure than all wordless sacrifices’;[2] gratitude to God should also be expressed ‘through a word’;[3] before every other offering God should be honoured by means of words, which are ‘common and unanimous offering of all those who have partaken of the divine grace’.[4] The Incarnation of the Word of God makes it possible for humans to speak of God Whom ‘no man hath seen at any time’, but Whom the incarnate Son of God ‘hath declared’, or revealed, explained (exegesato) to people.[5] From the moment when the Word of God explained the ‘unknown God’ to the human race, the task is laid on the ministers of the Word to continue this explanation and to speak to people about God. In other words, Christian theology is the continuation and development of Christ’s message.

            Human word cannot express God but can lead to Him, in the same manner as human reason cannot comprehend God but can approach Him. This is why Gregory regarded word as his only true wealth and the ministry of the word as his only true vocation: 

This is what I offer to God, this is what I consecrate, the only thing which I preserved for myself, which is my only possession. For I abandoned the rest, according to the Spirit’s commandment, and I exchanged everything what I ever had for one most precious stone...[6] As a minister of the Word I attach myself to word only,[7] and will never deliberately neglect it, but I highly value it, I greet it and I rejoice about it more than anything else... I make it friend of my whole life, my good counselor and companion, my guide on the way towards the high... All my desire is directed to word, after God, or better to say, to God himself, because it leads to God with the help of intelligence, through which - and only through which - God is comprehended by us, is preserved and grows in us.[8] 

            Gregory’s entire life consisted of periods of preaching and periods of silence. After his ordination to the priesthood he departed into the desert in order to spend some time in silence; he then returned to his father’s flock asking forgiveness. He acted in the same way after his episcopal ordination. Even during his later years as a Bishop he used to interrupt his activity as a preacher with periods of silence; he preserved silence for the entire period of Lent before Easter. Gregory was convinced that a purified word, a word about what is beyond words, reason and hearing cannot be born but from silence: 

You do not know what gift of God is silence, as well as not to be in need of any word, so that on one’s own accord to choose one thing and to avoid another thing, and to be for oneself a dispenser of both words and silence. For every word is by nature weak and shakable... but the word about God is as much more as its object is greater, zeal is stronger and danger more pressing. What are we afraid of, and what shall we set our hopes upon? Shall we set our hopes on our intellect or word or hearing? But there is danger for all three of them. For it is difficult to comprehend (God), it is impossible to express (Him),[9] and the most difficult of all is to find a purified hearing.[10] 

            In Gregory’s understanding, the ministry of the word must include apophatic silence alongside sermon: this is the nature of theology, which deals with what is beyond words. Gregory speaks of himself as God’s organ,[11] which is played by the Holy Spirit. When it is pleasing to Him, the organ sounds; at other times it is silent: 

I opened my mouth and attracted the Spirit,[12] and I give everything which is mine, as well as myself, to the Spirit: action and word, inaction and silence. Let Him possess me, let Him lead my hand, intellect and tongue to what is due and to what He wants... I am a divine organ, an instrument of word, which is tuned and played by the good artist, Spirit. Did he produce silence yesterday? So my philosophy was not to speak. Does he pluck the strings of the intellect today? I will pronounce word and my philosophy will be to speak... I close my door and disclose it for the Intelligence, the Word and the Spirit, united in nature and divinity.[13] 

            Word and silence are two wings with which the human intellect takes wing towards God. In the same manner negation and affirmation, apophaticism and cataphaticism are two ways by which a theologizing reason can approach its goal. Theology will be integral and authentic only when it recognizes that God is a mystery beyond words. In this case every word emerges from the feeling of weakness and helplessness of the human tongue in the face of this mystery. Every priest, bishop, theologian, every Christian is called to preach God, but their word must be born of prayer, and his prayer, from silence.