The document, released July 5, completes a papal trilogy on the three "theological virtues," following Pope Benedict XVI's encyclicals "Deus Caritas Est" (2005) on charity and "Spe Salvi" (2007) on hope. Publication of the encyclical was one of the most awaited events of the Year of Faith which began in October 2012.

Pope Benedict "had almost completed a first draft of an encyclical on faith" before his retirement in February 2013, Pope Francis writes, adding that "I have taken up his fine work and added a few contributions of my own."

Commentators will likely differ in attributing specific passages, but the document clearly recalls the writings of Pope Benedict in its extensive treatment of the dialogue between faith and reason and its many citations of St. Augustine, not to mention references to Friedrich Nietzsche and Fyodor Dostoyevsky.

On other hand, warnings of the dangers of idolatry, Gnosticism and Pharisaism, a closing prayer to Mary as the "perfect icon of faith," and an entire section on the relevance of faith to earthly justice and peace echo themes that Pope Francis has already made signatures of his young pontificate.

"Lumen Fidei" begins with a brief survey of the biblical history of faith, starting with God's call to Abraham to leave his land -- "the beginning of an exodus which points him to an uncertain future" -- and God's promise that Abraham will be "father of a great nation."

The Bible also illustrates how men and women break faith with God by worshipping substitutes for him.

"Idols exist, we begin to see, as a pretext for setting ourselves at the center of reality and worshipping the work of our own hands," the pope writes. "Once man has lost the fundamental orientation which unifies his existence, he breaks down into the multiplicity of his desires ... Idolatry, then, is always polytheism, an aimless passing from one lord to another."

Pope Francis sees another way of turning from God in the Pharisees' belief that salvation is possible through good works alone.

"Those who live this way, who want to be the source of their own righteousness, find that the latter is soon depleted and that they are unable even to keep the law," the pope writes. "Salvation by faith means recognizing the primacy of God's gift."

Faith finds its fulfillment in the life, death and resurrection of Jesus Christ, the pope writes. By virtue of his humanity, Jesus is both the object of faith and the ultimate model and mediator for all believers.

"Christ is not simply the one in whom we believe, the supreme manifestation of God's love," Pope Francis writes. "He is also the one with whom we are united precisely in order to believe. Faith does not merely gaze at Jesus, but sees things as Jesus himself sees them, with his own eyes: it is a participation in his way of seeing."

This participation means that faith inevitably makes a Christian part of Christ's mystical body, the church.

"It is impossible to believe on our own," the pope writes. "By its very nature, faith is open to the 'we' of the church; it always takes place within her communion."

The church transmits the faith across time "through an unbroken chain of witnesses," allowing us to "see the face of Jesus," Pope Francis writes. "As a service to the unity of faith and its integral transmission, the Lord gave his church the gift of apostolic succession. Through this means, the continuity of the church's memory is ensured and certain access can be had to the wellspring from which faith flows."

Accordingly, members of the hierarchy stand as the authoritative teachers of the contents of Christian faith.

The "magisterium of the pope and the bishops in communion with him," the pope writes, "ensures our contact with the primordial source and thus provides the certainty of attaining to the word of Christ in all its integrity."

Yet faith in its fullness is more than doctrine, Pope Francis writes; it is "the new light born of an encounter with the true God, a light which touches us at the core of our being and engages our minds, wills and emotions, opening us to relationships lived in communion."

Thus the primary means of transmitting faith is not a book or a homily, but the sacraments, especially baptism and the Eucharist, which "communicate an incarnate memory, linked to the times and places of our lives, linked to all our senses; in them the whole person is engaged as a member of a living subject and part of a network of communitarian relationships."

The belief that the "Son of God took on our flesh" and "entered our human history" also leads Christians "to live our lives in this world with ever greater commitment and intensity," the pope writes, arguing that faith inspires both the use of human reason and pursuit of the common good.

For faith, Pope Francis writes, truth is not attainable through autonomous reason alone but requires love, a "relational way of viewing the world, which then becomes a form of shared knowledge, vision through the eyes of another and a shared vision of all that exists."

By affirming the "inherent order" and harmony of the material world, and "by stimulating wonder before the profound mystery of creation," Christian faith encourages scientific research, while dispelling the philosophical relativism that has produced a "crisis of truth in our age."

Faith also inspires respect for the natural environment, by allowing believers to "discern in it a grammar written by the hand of God and a dwelling place entrusted to our protection and care."

According to Pope Francis, faith has proven itself essential to the promotion of "justice, law and peace," by contrast with failed modern ideologies that also claimed those goals.

"Modernity sought to build a universal brotherhood based on equality," he writes, "yet we gradually came to realize that this brotherhood, lacking a common reference to a common father as its ultimate foundation, cannot endure.

"We need to return to the true basis of brotherhood," the pope writes. "Faith teaches us to see that every man and woman represents a blessing for me, that the light of God's face shines on me through the faces of my brothers and sisters."

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To read the full encyclical, visit The Vatican website.