Question: "What was the Enlightenment, and what impact did it have on Christianity?"

Answer: The Enlightenment is often referred to as the “Age of Reason” and developed in the early-to-mid-17th century from three primary geographical hubs; France, Germany, and Great Britain (including Scotland). The Enlightenment was marked by changes in thought that contrasted sharply with the philosophies of preceding eras. Enlightenment thinkers cast off much of the religious, philosophical, and political ideals of previous generations and forged new ground.

The Enlightenment is generally taken to begin with the ideas of Descartes and culminate with the French Revolution in the late 18th century. The intellectual movement spans the better part of 150 years and had a profound impact on Western culture. In particular, the fields of philosophy, science, and politics were forever changed.

Major Aspects of the Enlightenment: Philosophy

One of the major philosophical developments of the Enlightenment was rationalism. René Descartes introduced rationalism into philosophical thought, starting with his system of methodical doubt. Descartes’ work encouraged other thinkers to question longstanding cultural assumptions, as well as their own presuppositions. The predominant theme of rationalism is that concepts and knowledge can be gained independently of sense experience—we can think our way to truth. By emphasizing the power of the mind over the senses, rationalism provided a framework for philosophers to push the limits of what can be known by human reason alone. Baruch Spinoza, a notable rationalist, posited what amounts to a type of scientific pantheism. In Spinoza’s view, there is only one kind of substance, and God and nature are therefore identical. Spinoza’s thought provided license for later developments that focused on the mechanization of the natural world. Other notable rationalist thinkers were Christian Wolff and G. W. Leibniz, who each made deep and lasting impacts in philosophy (Leibniz in calculus, as well).

Partly in response to rationalism, and partly of its own accord, empiricism also developed during the Enlightenment. In contrast to rationalism, empiricism holds that knowledge begins with the senses. Francis Bacon planted the seed for empiricist thought that came to fruition in the physics of Isaac Newton. Since natural science begins with observation through the senses, the scientific revolution could not have occurred without an empiricist philosophical underpinning. The notions of observation and induction are part and parcel of empiricism. John Locke developed his famous analogy of tabula rosa (“blank slate”) to describe the mind as ideas come into it from the senses.

Skepticism also developed during the Enlightenment. David Hume famously spread doubt about whether knowledge can be obtained at all—from the senses or from reason. Hume’s conclusions led down a road that results in, at best, only probabilistic reasoning to possible conclusions. Hume also presented a significant challenge to science with his critiques of causality and inductive reasoning. These skeptical arguments and causal notions have resonated in both philosophy and science to the present day.

An important note about Enlightenment philosophical thought is the noticeable shift away from metaphysics and toward epistemology. Metaphysics, the study of what is ultimately real and/or supersensible, was supplanted by a focus on the process of knowing; i.e., what one knows was replaced by how one knows (if one can know anything at all). The scientific revolution, with its implicit focus on understanding the natural world, made it easier for Enlightenment thinkers to either move away from metaphysics (as it was traditionally understood) or to subsume it under a rationalist motif. It should also be noted that the philosophy of Immanuel Kant was developed in large part as a response to problems raised with Enlightenment philosophy.

Major Aspects of the Enlightenment: Science

The crowning scientific achievement of the Enlightenment was Isaac Newton’s seminal work Principia Mathematica (1687). In this work, Newton sets the tone for a mechanistic understanding of the natural world by explaining a wide range of phenomena via mathematical formulas. Given that things previously thought to be unquantifiable or unpredictable in nature could, under Newton’s system, be understood in terms of a machine-like entity. Nature, therefore, became a thing that man could inquire into, harness, and use for bettering his lot in life. And Newton, therefore, is known today as the father of modern science.

The greatest scientific benefits of Newtonian mechanics would not be felt until after the Enlightenment, but the increasingly prevalent notion of nature as describable and predictable impacted other fields during the 18th century. Important advances were made in biology, chemistry, and medicine. Carl Linnaeus developed a formalized system of biological taxonomy that was important to biology and paleontology as those specialized studies emerged.

The French Encyclopedists, such as Diderot and d’Alembert, played an important role in proselytizing on behalf of science. By emphasizing the work of Bacon and Newton in their publications, the Encyclopedists pushed forward an agenda of secular thought and open-mindedness. Through the Encyclopédie, Enlightenment thought was brought to bear in a systematic way that helped it become easier to understand and utilize.

Major Aspects of the Enlightenment: Politics

The lasting political impact of the Enlightenment cannot be overstated. At least three major political revolutions occurred during this time period in Britain, America, and France. These revolutions manifested ideas centering on government by consent of the governed, social contract, freedom, and equality. In the mid-17th century, philosopher Thomas Hobbes advanced the notion of the absolute power of government over the governed for the sake of avoiding barbarism. Hobbes also advanced ideas about social contract and the relation of the individual to the state that both Locke and Rousseau later took up.

Locke was a tremendously important political philosopher during the Enlightenment. Many of his ideas and principles were studied and adopted by the founders of America and are evident in documents like the Declaration of Independence and the Constitution. Locke emphasized the natural freedom of human beings, the equality of all before God, natural law, and government by consent of the governed; and he justified the overthrow of government when it fails. Jean-Jacques Rousseau was another prominent thinker from the Enlightenment era. Rousseau differed with Locke about the role of the individual in relation to the state, with Rousseau emphasizing the importance of the governed being involved in politics.

The Enlightenment’s Impact on Religion

Religion was an oft-discussed topic of the Enlightenment. It is important to view this period in light of the Protestant Reformation that preceded it. The monolithic nature of the church had come to an end, and Enlightenment thinkers had already been freed, to a large degree, by the dialogue and writings that came out of the Reformation. It should be noted that many prominent thinkers of the Enlightenment were Christians, although some were unorthodox in their beliefs. Primary themes of Enlightenment thought on religion center on the notions of anti-supernaturalism, deism, and, as it relates to Christianity, biblical criticism.


Due to the emphasis on rationalism (seeking that which can be known a priori—before experience—by the mind alone) and empiricism (seeking that which can be known and verified by the senses and/or instrumentation), a great bulk of Enlightenment thought was skeptical of the supernatural. This would especially include the Bible’s record of miracles. The physical science of the day, with the new revelation of the world as a mechanism that obeys laws, threw serious doubt on claims that anything in nature could occur contrary to its regular operation. Spinoza famously critiqued the notion that nature can act against itself. Hume emphasized the idea that miracles are violations of the laws of nature. Because man could, by the power of reason, throw off the shackles of patristic institutions and think for himself to logical conclusions, it seemed to many in the Enlightenment that miracles or immaterial things (such as angels or demons) were simply relics of past superstition. This anti-supernatural thought provided the groundwork for atheism to become more mainstream. If God is a supernatural/supersensible being, then it was possible that belief in Him was simply irrational tradition.


In contrast to theism (belief in a single, personal creator and sustainer of all there is), deism teaches that whatever supreme intelligence created and/or organized the cosmos does not intervene in creation. The analogy of a watchmaker is frequently used to describe deistic thinking. According to deism, God simply wound up the watch of the universe, stepped back, and let it run. Things like prayer, special revelation, and a personal relationship with God are nonsensical. The natural law, derived from man’s study of nature through the sciences, is what governs morality and human conduct. Religious texts like the Christian Bible are perhaps helpful moral guides but not genuine revelation from God.

Biblical Criticism

Biblical criticism, the study of the biblical texts as ordinary historical literature, did not come to the forefront of academic work until the 19th century. However, without the anti-supernatural foundation and skeptical thought of the Enlightenment, it is unlikely that biblical criticism would have had such a lasting cultural impact. The evaluation of any historical text is a valuable pursuit, but, ironically, biblical criticism began with Enlightenment assumptions; it started by assuming certain scientific, mechanistic, and naturalistic notions and looked at the Bible in that light.

Starting with Hobbes and Spinoza, biblical criticism took on many facets, including textual, source,redaction, canon, and form criticism. But the entire study takes on a different context under the Enlightenment paradigm. The Bible is a book filled with accounts of miracles, so, once supernatural events are dismissed as impossible, the entire reading changes. If theism is a priori ruled out, then the credibility of what is recorded in the Bible is undermined from the outset. Speculation becomes much easier from this platform, and many theories, such as one denying the literal reality of Jesus of Nazareth, took shape. Through the years, the criticisms of the Bible put forward by Enlightenment philosophy have been strongly refuted by careful scholarship.


The Enlightenment is deserving of study for many reasons, not the least of which is to better understand how the thoughts of that period shaped ensuing years. Like any other epoch considered through the lens of history, there is much commendable and much lamentable about the Enlightenment. One should be careful to take the helpful notions and leave the genuine vestiges behind. Just as we are to test all prophecies and hold on to what is good (1 Thessalonians 5:21), so we should put Enlightenment philosophies to the test and dispense with the false.