The encyclical Lumen Fidei is the first document of Pope Francis’ pontificate. We suggest that our readers review numbers 1-4 (see below), which summarize the symbolism of light in reference to faith, as they appear in Sacred Scripture and are discussed in the patristic and theological Tradition (for interested visitors: the complete text is available on the Holy See web site). These paragraphs offer a short historical account of the evolution of the conception of faith as “light”, ranging from the novelty brought by Christianity in the pagan Roman world to modern thought’s critique of it, and conclude by affirming the value of the light of faith not only for Christians, but also for every man and woman.
1. The light of Faith: this is how the Church’s tradition speaks of the great gift brought by Jesus. In John’s Gospel, Christ says of himself: "I have come as light into the world, that whoever believes in me may not remain in darkness" (Jn 12:46). Saint Paul uses the same image: "God who said ‘Let light shine out of darkness,’ has shone in our hearts" (2 Cor 4:6). The pagan world, which hungered for light, had seen the growth of the cult of the sun god, Sol Invictus, invoked each day at sunrise. Yet though the sun was born anew each morning, it was clearly incapable of casting its light on all of human existence. The sun does not illumine all reality; its rays cannot penetrate to the shadow of death, the place where men’s eyes are closed to its light. "No one — Saint Justin Martyr writes — has ever been ready to die for his faith in the sun". Conscious of the immense horizon which their faith opened before them, Christians invoked Jesus as the true sun "whose rays bestow life".  To Martha, weeping for the death of her brother Lazarus, Jesus said: "Did I not tell you that if you believed, you would see the glory of God?" (Jn 11:40). Those who believe, see; they see with a light that illumines their entire journey, for it comes from the risen Christ, the morning star which never sets.
2. Yet in speaking of the light of faith, we can almost hear the objections of many of our contemporaries. In modernity, that light might have been considered sufficient for societies of old, but was felt to be of no use for new times, for a humanity come of age, proud of its rationality and anxious to explore the future in novel ways. Faith thus appeared to some as an illusory light, preventing mankind from boldly setting out in quest of knowledge. The young Nietzsche encouraged his sister Elisabeth to take risks, to tread "new paths… with all the uncertainty of one who must find his own way", adding that "this is where humanity’s paths part: if you want peace of soul and happiness, then believe, but if you want to be a follower of truth, then seek". Belief would be incompatible with seeking. From this starting point Nietzsche was to develop his critique of Christianity for diminishing the full meaning of human existence and stripping life of novelty and adventure. Faith would thus be the illusion of light, an illusion which blocks the path of a liberated humanity to its future.
3. In the process, faith came to be associated with darkness. There were those who tried to save faith by making room for it alongside the light of reason. Such room would open up wherever the light of reason could not penetrate, wherever certainty was no longer possible. Faith was thus understood either as a leap in the dark, to be taken in the absence of light, driven by blind emotion, or as a subjective light, capable perhaps of warming the heart and bringing personal consolation, but not something which could be proposed to others as an objective and shared light which points the way. Slowly but surely, however, it would become evident that the light of autonomous reason is not enough to illumine the future; ultimately the future remains shadowy and fraught with fear of the unknown. As a result, humanity renounced the search for a great light, Truth itself, in order to be content with smaller lights which illumine the fleeting moment yet prove incapable of showing the way. Yet in the absence of light everything becomes confused; it is impossible to tell good from evil, or the road to our destination from other roads which take us in endless circles, going nowhere.
4. There is an urgent need, then, to see once again that faith is a light, for once the flame of faith dies out, all other lights begin to dim. The light of faith is unique, since it is capable of illuminating every aspect of human existence. A light this powerful cannot come from ourselves but from a more primordial source: in a word, it must come from God. Faith is born of an encounter with the living God who calls us and reveals his love, a love which precedes us and upon which we can lean for security and for building our lives. Transformed by this love, we gain fresh vision, new eyes to see; we realize that it contains a great promise of fulfilment, and that a vision of the future opens up before us. Faith, received from God as a supernatural gift, becomes a light for our way, guiding our journey through time. On the one hand, it is a light coming from the past, the light of the foundational memory of the life of Jesus which revealed his perfectly trustworthy love, a love capable of triumphing over death. Yet since Christ has risen and draws us beyond death, faith is also a light coming from the future and opening before us vast horizons which guide us beyond our isolated selves towards the breadth of communion. We come to see that faith does not dwell in shadow and gloom; it is a light for our darkness. Dante, in the Divine Comedy, after professing his faith to Saint Peter, describes that light as a "spark, which then becomes a burning flame and like a heavenly star within me glimmers". It is this light of faith that I would now like to consider, so that it can grow and enlighten the present, becoming a star to brighten the horizon of our journey at a time when mankind is particularly in need of light.
from Franciscus, Encyclical Lumen Fidei, 2013, June 29, nn. 1-4.
 Dialogus cum Tryphone Iudaeo, 121, 2: PG 6, 758.
 Clement of Alexandria, Protrepticus, IX: PG 8, 195.
 Brief an Elisabeth Nietzsche (11 June 1865), in: Werke in drei Bänden, München, 1954, 953ff.
 Paradiso XXIV, 145-147.