The four books of the Summa contra Gentiles were written by Thomas Aquinas between 1259-1265, before the considerably larger and more influential, Summa Theologica. The purpose of each work was different. Whereas the Summa Theologica addressed the faithful, especially theology students, the intention of the Summa Contra Gentiles (Systematic Exposition Against Non-Christians) was to speak to a non-aligned and even hostile audience. To that purpose, Aquinas presented arguments ‘refuting specific beliefs or heresies.'

In this famous treatise, St. Augustine (AD 354 - 430) covers the question of the role of free will in our lives and how it contrasts with the role of God's grace. He gives scriptural arguments to show that we cannot earn the grace of God, yet this does not deny the role that free will plays in our own salvation.

The Enchiridion, or as it is sometimes titled, Faith, Hope, and Love, is a short treatise on Christian piety, written in response to a request soon after the death of St. Jerome in 420. The essay was meant to serve as a model for Christian instruction (catechesis).

From the perspective of an unbeliever, Fear and Trembling explores the paradox of faith, the nature of Christianity, and the complexity of human emotion. Kierkegaard examines the biblical story of Abraham, who was instructed to sacrifice his son Isaac, and forces us to consider Abraham's state of mind. What drove Abraham, and what made him carry out such an absurd and extreme request from God? Kierkegaard argues that Abraham's agreement to sacrifice Isaac, and his suspension of reason, elevated him to the highest level of faith.

The work constitutes an exposition of the several clauses of the so-called Apostles’ Creed. The questions concerning the mutual relations of the three Persons in the Godhead are handled with greatest fullness; in connection with which, especially in the use made of the analogies of Being, Knowledge, and Love, and in the cautions thrown in against certain applications of these and other illustrations taken from things of human experience, we come across sentiments which are also repeated in the City of God, the books on the Trinity, and others of his doctrinal writings. The passage ...

This book was written in Latin by Augustine of Hippo (354 - 430) to discuss the Trinity in relation to God the Word (logos). Even though it is not as well known as some of his other writings, it is considered by many to be his masterpiece and of more doctrinal importance than either the Confessions or the City of God. St. Augustine is considered a saint in the Catholic Churches, the Eastern Orthodox Church, and the Anglican Communion. He is ranked among the doctors of the Church in the Roman Catholic Church.

Recognizing Paul’s words to the Galatians as crucial to understanding the truth of God’s saving grace, Martin Luther set out to examine this great work verse by verse, especially for those led astray by the teachings of false gospels. All of Luther’s writings, including this commentary, directly combat the direction of the Catholic church at the time that strove to portray salvation as a thing to be earned and then mediated through religious leaders.

In The Story of Christianity, Vol. 1, Justo L. González, author of the highly praised three-volume History of Christian Thought, presents a narrative history of Christianity from the early church to the dawn of the Protestant reformation. From Jesus' faithful apostles to the early reformist John Wycliffe, González skillfully traces core theological issues and developments within the various traditions of the church, including major events outside of Europe, such as the Spanish and Portuguese conquest of the New World.

In this exposition of 1 Corinthians 13, Jonathan Edwards delves into the crucial Christian discussions of grace, love, and salvation. In doing so, he reveals their natural relations to one another and how living in grace should inevitably lead to living with love. This work does not simply explain the passage, but it also serves as a practical guide of how to live out a life of love.

Robert Barron is one of the Catholic Church's premier theologians and author of the influential The Priority of Christ. In this volume, Barron sets forth a thoroughgoing vision for an evangelical catholic theology that is steeped in the tradition and engaged with the contemporary world. Striking a balance between academic rigor and accessibility, the book covers issues of perennial interest in the twenty-first-century church: who God is, how to rightly worship him, and how his followers engage contemporary culture.