John Locke (1632—1704) was a British philosopher, academic, and medical researcher. His best-known and most influential philosophical works include An Essay Concerning Toleration (1667), An Essay Concerning Human Understanding (1690), and The Reasonableness of Christianity (1695).
In An Essay Concerning Human Understanding, Locke examines how people can know things and the limits of human understanding. He sets forth the principle that there are some things that could have been revealed by God but that people can also discover on their own. Principles of mathematics and human anatomy are examples of things can be discovered using human reason. However, there are other things that could never be discovered by human reason, and they must be revealed by God if we are to know them. The Trinity and the nature of angels are examples of things that we could never discover on our own. These sorts of things must be accepted by faith and cannot be evaluated by reason.
Locke did not believe that reason has no place in the Christian life. While the content of divine revelation cannot be evaluated by reason, we should use reason to evaluate whether or not actual divine revelation has taken place. The claim that someone has received revelation should be rationally verified before it is believed. Locke warned against the dangers of “enthusiasm,” which was becoming popular at the time and still expresses itself today in many Christian groups that emphasize emotion and direct personal revelation. He warned that the excitement of personal revelation can often overrule the rational faculties and cause some people to believe things that were not actually revealed by God. He also makes this point in The Conduct of the Understanding and the Reasonableness of Christianity. According to Locke, abandoning reason in favor of personal revelation leads to “odd opinions and extravagant actions.” Unfortunately, Locke’s warning is unheeded in many churches today, and some engage in all kinds of odd and extravagant actions.
John Locke also put forward arguments for the existence of God, the possibility of miracles, and the deity of Christ. However, the most lasting impact upon Christianity came from his writings on ethics and government. Locke held that natural law (also expressed in the Golden Rule) teaches us that “being all equal and independent, no one ought to harm another in his life, health, liberty or possessions; for men being all the workmanship of one omnipotent and infinitely wise Maker” (from An Essay Concerning Toleration). It was from John Locke that Thomas Jefferson got the ideas he expressed in the Declaration of Independence: “We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.” The freedom of American society allowed Christianity to flourish and for Christians to accumulate wealth that has been used over the centuries to fund mission endeavors worldwide. The American ideals of democracy and tolerance are due in large part to the heavy reliance of the Founding Fathers on the writings of John Locke. To the extent that the United States has been able to sway other governments in the direction of freedom and tolerance, those governments have been more tolerant of Christians within their borders. As American society strays further and further from the principles articulated by John Locke, Christian morality becomes increasingly intolerable, and Christians become more susceptible to persecution.