With the development in Western theology of increasingly sharp distinctions between nature and grace, the natural and the supernatural, and reason and revelation, theologians became interested in what truths about God could be established by reason alone. Called natural theology (theologia naturalis), as opposed to revealed theology (theologia revelata), this discipline became particularly important in arguments between Christians on the one hand and Jews and Muslims on the other, because the arguments of natural theology did not depend on the acceptance of revelation.
The systematic presentations that characterized Western theology in the 13th century (the age of the Schoolmen, or Scholastics) were often prefaced by an account of what could be established by reason about God; usually the first thing to be established was his existence. The most famous set of such arguments is the so-called Five Ways of St. Thomas Aquinas, which appears in his greatest work, the Summa theologiae (1265/66–1273). Aquinas claimed to have established the existence of God as the unmoved mover, as the ultimate efficient cause, as the necessary being, as the perfect being, and as the final cause of all beings. For Aquinas, such natural theology was part of the sacra doctrina (“sacred doctrine”) of the church.
The century following Aquinas was marked by the development of the “theology of the two powers,” which distinguished between what God can do absolutely (potentia absoluta), or logically, and what he has bound himself to do in accordance with the covenant he established with humankind (potentia ordinata). This distinction helped sharpen the division between what is necessarily so, which could be explored by reason, and what God has revealed about himself and his relations with humankind. The contrast between reason and revelation was reflected in the continued development of natural theology and revealed theology .
In the late Middle Ages a further division occurred between “rational theology” (which usually embraced both natural and revealed theology) and a theology of felt experience, often called “mystical theology,” a designation consciously borrowed from Pseudo-Dionysius. Mystical theology came to be identified with the experience of God and with contemplation of the divine. An alternative approach, known as “ascetical theology,” involved seeking God through a life of prayer, devotion, self-denial, and mortification. The Renaissance, the Reformation, and the Enlightenment
During the Renaissance, medieval theology suffered further fragmentation, but theologians also acquired new conceptual tools. The late-medieval conception of Christianity had emphasized its contingent nature, its truth being not a logical necessity but the result of the will of God. Although few, if any, of the thinkers of the Renaissance wished to undermine Christianity, their awareness of its contingency led them to look for some underlying truth, a “primordial revelation” that would make sense of both Christianity and the religions of classical and late antiquity. This truth was often identified with the so-called Hermetic wisdom attributed to Hermes Trismegistos (Hermes the Thrice-Greatest), the Greek name of Thoth, the Egyptian god of writing. Although Hermetic teachings were thought to be of unimaginable antiquity, in reality the writings from which they were drawn (the Hermetic writings) date from only the mid-1st to the late 3rd centuries.
The theology of the primordial revelation was called pristina theologia (“pristine theology”), or the theology of human primal innocence. Pristina theologia provided the starting point for many attempts by thinkers of the Renaissance to penetrate behind the faded texture of the religious systems of their day to what was thought to be some ultimate forgotten truth. Often it was studied in combination with mystical theology, which was thought to authenticate pristina theologia by providing a felt experience of the ultimate. Out of this potent mixture emerged the Renaissance revival of alchemy, movements such as the Rosicrucians, and the elaborately symbolic mysticism of the German thinker Jakob Böhme (1575–1624).
With the turn of the 18th century, the ideas of the Renaissance came to assume a somewhat more somber hue: pristina theologia yielded to natural religion—that is, the principles of religion that can be established by reason alone (e.g., that God exists). Natural religion was then contrasted with positive religion, or the particular religious traditions of different societies or cultures. This distinction would become axiomatic in Protestant theology during the Enlightenment and in much of the post-Enlightenment period. The Enlightenment belief in the contingent nature of revelation led scholars of the period to treat the sacred books of Christianity as historically determined rather than as witnesses to, or embodiments of, divine revelation. This conception soon created, as the German writer Gotthold Lessing described it, an “ugly, broad ditch” between the history to which the Scriptures belonged and bore witness and the eternal truths that the dogmatic systems had derived from them. The 19th century to the present
In the 19th century, European colonialism led to the rediscovery, translation, and publication of a wealth of sacred writings from the indigenous cultures of Asia and Africa, which encompassed both living religions—especially Hinduism and Buddhism—and religions of antiquity, especially those of Egypt. Treatises of the Hermetic tradition and codices containing texts of the gnostics were discovered during the 19th and 20th centuries. Access to such a hitherto unimaginable richness of religious traditions led to many attempts to explore and draw connections between them, often using theological categories drawn from Christianity. It also led to a revival of the Renaissance quest for some ultimate religion underlying them all, though the geographical source of such a pristina theologia was generally thought to lie much farther to the east than ancient Egypt.
Christian theology itself was not unaffected by these discoveries, though it was more immediately affected by other currents, notably from the Enlightenment. Attempts were made during the 19th century to leap across the ditch that Lessing had lamented—notably by the Danish philosopher Søren Kierkegaard—but the long-term effect was further fragmentation of Protestant (and eventually Roman Catholic) theology, leading to the separation of biblical theology (the theological study of God’s progressive revelation of himself through the stages of biblical history) from dogmatic or systematic theology. This tendency was further accelerated by the increasing academic independence of universities (where theology had generally been studied). Eventually, several additional theological subdisciplines emerged, including Old Testament theology, New Testament theology, church history (or sometimes historical theology), pastoral or practical theology, and even “spiritual” theology, often understood as a combination of ascetic and mystical theology. This fragmentation of theology cast into doubt the coherence of the whole enterprise.