I have compiled a list of who I think the ten most important theologians outside of the New Testament in the church are. Anyone disagree with my assesment? Feel free to comment.
1. Augustine- Augustine is simultaneously the father of Roman Catholicism, Calvinism and Lutheranism. His high view of the church was adopted by the Romish church, his view of grace was adopted by the Lutheran and Reformed churches, and his view of the sovereignty of God became the cornerstone of Calvinism. Also the mystic and scholastic movements could claim themselves as heirs of Augustine. He has done great things for the universal church by giving the clearest explenation of the trinity which the western church would ever have in his book on the Trinity. He defined original sin much clearer than any theologian before him, securing this position for all of the western church. Because of his doctrine of original sin, the theological foundation for infant baptism was secured, not to be questioned for hundreds of years. Augustine's book the City of God influenced both the theocracy under Charlamagne and the two kingdom theology of Luther. Augustine's treatise on the Spirit and the Letter was the first clear explanation of what would later be known as the Lutheran law/gospel distinction. Also, the universalism that many had speculated about since the time of Origen was finally wiped out by Augustine.
2. Martin Luther- Martin Luther was of course the father of the Protestant reformation, one of the most important events in the history of the church (and the world in general). He defined the doctrine of justification by faith alone clearer than any had before him. Paul's theology for the first time was fully understood. Luther pushed the whole church to go back the scripture as the only infallible source of truth. He helped abolish the idea that good works were done by seperating oneself from society and trying to save himself. Good works are those things done for the benefit of one's neighbor. Monasticism was not a higher form of spirituality than that of a baker, and it certainly was not a "second baptism." In short, Luther helped the church rediscover the gospel.
3. Athanasius- He made two major theological claims which effected the church for the rest of history. First, his work On the incarnation of the word was the first book written on the atonement, the center of Christianity. In this treatise, Athanasius supports the idea that we all owe a debt of death to God because of our sin. Christ took this debt upon Himself, so that we could be redeemed. Not only are we forgiven of our sins, but God then conforms us to the image of His son. His second major accomplishment was his defense of the deity of Jesus Christ. Athanasius defended at one point against most of the church that Christ was of one substance with the father. He was kicked out of the empire several times for defending the truth. He was the major figure behind the definition of Nicea.
4. John Calvin- Calvin did not do much that was new. However, he formulated a doctrinal system which would effect all of Protestantism outside of Lutheranism. He defined the idea of double predestination which would become a central tenant of the reformed church. He went farther than Luther with the idea of sola scriptura by creating the regulative principle of worship. Man is only to include in a worship service that which is directly commanded by God. He formulated a view of governent which became the ideology of the Puritans when they came to establish America. The most positive thing Calvin did was emphasize the grammatical historical method of Bible interpretation. It surely was taught by many before Calvin, but he did it with excellence, not surpassed by perhaps any since his time.
5. Thomas Aquinas- He is considered the "angelic doctor" of the Roman church. He put together the most comprehensive system of theology ever produced, which layed the groundwork of modern day Roman Catholicism. He popularized the use of Aristotle in Christian theology and the use of natural theology. According to Aquinas, man's intellect was not fallen, though his will was. He was the most important figure to come out of the scholastic period.
6. Friedrich Schleiermacher- He is the father of Protestant liberalism. When the enlightenment came, many became deists and rejected religion all together. Schleiermacher did not want to do this and so he claimed to be a Christian theologian while rejecting almost every cardinal doctrine of the Christian faith. His unfortunate influence is still with us today and was the cause of the Bible wars in the 20th century.
7. Karl Barth- He formed neo-orthodoxy, the midway point between conservativism and liberalism. He accepted some of the historical critical ideas, but did not want to reject the theology of the Protestant Reformers. Barth put the Bible back in an authoritative place and rejected natural theology. Christ was once again placed at the center of the Christian faith. Barth's influence has been both positive and negative. Positive in his Christocentrism, yet negative in his denial of innerancy.
8. Gregory the Great- He defined what would be the religion of the middle ages. He marks the end of the age of the fathers and the dawn of a new era. He liked Augustine but toned down his theology of predestination, coming closer to the semi-pelagian position. While rejecting the title of universal bishop, he got himself involved in political affairs, laying the groundwork for the Papal theocracy of a later period. He popularized the idea of purgatory which led to the focus on the meritorious nature of penance and prayers to the saints as mediators between man and Christ. In some ways, Gregory is the first Roman Catholic.
9. John Wesley- The founder of methodism, he popularized Arminianism and led way to a new branch of the Protestant church. As an evangelist, he did many good things, preaching both law and gospel. Under Wesley, experience became essential to the Christian life. One must have an experience of grace and come to a point where God assures him of his salvation. Wesley fought against much of the legalism in the Anglican church of his day, emphasizing the gratuity of God's grace. In doing this he rejected Calvinism while defending the idea of prevenient grace. He came up with the idea of perfectionism, which taught that the Christian could come to a point in his life when he would no longer sin. This led to the second blessing idea which was then the foundation of pentacostalism.
10. Charles Finney- He was the leader of the so-called "second great awakening." Rather than emphasizing the sinfulness of man and the free grace of God in Christ, as Wesley, Edwards, and Whitfield did in the first awakening, Finney emphasized the experience of conversion. Finney denied original sin and the substitutionary atonement of Christ. For Finney, Christianity was about morality. One could be converted by an emotional experience and then live a good moral life. These ideas have become the basis for modern evangelicalism.