One of the many striking things in the election of Barack Obama as the next President of the United States is the power of his language. His gifts of oratory and rhetoric are palpable, rooted in ancient and classical means of communication, in which rhythm, alliteration and assonance all have their part to play. In his powerful repetition of questions and phrases, challenging and cumulative sentences end with some simple affirmation — “Yes, we can.”

Aristotle famously spoke of three aspects of arguments that convince — logos, pathos and ethos. The first is centred on logical reasoning, the second on emotional appeal, and the third has at its heart an ethical appeal, convincing by the character of the speaker or author. When there is a mismatch or a disjunction between powerful words spoken and the character of the speaker, then the accusation of hypocrisy is quick to be made. Oratory and rhetoric to be powerful and convincing need to be grounded in a life that is consonant with the ideals proclaimed. Words without moral commitment will never suffice. It is not merely Obama’s words that have swayed Americans and moved so many elsewhere, it is the sense that words and character match. Both politicians and preachers are judged by their integrity, the coherence of life and rhetoric.

At the beginning of this month I was privileged to be present at the reception of the relics of Cardinal John Henry Newman at the Oratory Church in Birmingham, where he ministered for the latter part of his long life. Shaped and formed by the Church of England, which he eventually left to join the Roman Catholic Church, Newman was acutely aware of the power of language and the need for the words of the preacher about Christ to inhere in a life which reflected Christ. Knowing Aristotle, he was well aware of the importance of ethos, that all deep knowledge, to use a later phrase of the philosopher of science, Michael Polanyi, was “personal knowledge”.

In 1832, in an Oxford University sermon, Newman spoke of “personal influence, the means of propagating the truth”. Some believed that that sermon was the real catalyst for the Oxford Movement of Catholic revival in the Church of England. As an Oxford tutor, Newman believed passionately in the personal and pastoral dimension of education. When he came to write The Idea of a University, he sharply condemned a university without the influence of teachers on pupils: “It would be an ice-bound, frozen, petrified university.” Both his understanding and his criticisms have continuing relevance for education in our own day. He attacked the shallow, utilitarian rationalism of a reading room at Tamworth from which all religious books had been excluded. “The heart,” he said, “is commonly reached not through the reason but through the imagination.” (And by the heart he meant, as the Bible does, not the place of feeling, but of willing and choosing.) Nothing anonymous, he says, will ever convert. There is an irreducible incarnational principle in all human passion for and exposition of truth.

When Newman was made a cardinal in 1879, he took as his motto “Cor ad cor loquitur” — “heart speaks to heart”, words of the 17th-century Francis de Sales, for whom it summed up the pastoral mission of the preacher and the teacher. Newman knew that the Christian faith could not be expressed in so many dumb documents. He believed deeply in the creeds, but they were always symbols of a faith that was not exhausted by them. The revelation of God in Christ was at heart a mystery, a well of life whose depths were only plumbed as the meaning of Christ was lived out and pondered on by the Church in the changing scenes of history.

The liturgical, sacramental and devotional life of the Christian community provides an ethos, a context of moral shaping and discipline that forms in us the mind of Christ. It is by living the life that we know the doctrine. Christ’s call to discipleship is a call to holiness, to Christ-likeness. As the writer of the Letter to the Hebrews puts it, God had spoken to us in many and varied ways, but in the last days he has spoken through His Son, the Christ who is “the image of the invisible God and the stamp of His very being”.

In incarnation God spoke to us. Those shaped by the Spirit in the likeness of Christ are saints whose speaking lives are the true rhetoric of God’s love.

The Right Rev Geoffrey Rowell is Bishop of Gibraltar in Europe