By Dulles, Avery Cardinal
First Things: A Monthly Journal of Religion and Public Life , No. 149
As Christianity spread throughout the Greco-Roman world, it became apparent that the biblical doctrines concerning God, morality, and future retribution had similarities with the philosophical speculations of the Platonists, Aristotelians, and Stoics. The Fathers and medieval theologians had no difficulty in admitting this; on the contrary, they saw it as a confirmation of the truth of revelation. Human reason at its best, they explained, is able to discover some of the doctrines that God revealed through the prophets and Jesus Christ.
This being granted, revelation was still necessary for two reasons. First, because even the naturally knowable truths were attained only by a few, and by them with great difficulty and a considerable admixture of error. Second, because certain truths very important for salvation could not be attained in any other way than by revelation accepted in faith. Among the truths in this second category were the Trinity, the Incarnation, the redemptive death of Christ on the Cross, his Resurrection and Ascension into glow, the institution of the Church, the sacraments, the bestowal of grace, and the beatific vision. Human reason could find solid reasons for believing the Christian revelation, but in the end the believer had to make a free and trusting commitment to the word of God. In that sense, faith was above reason.
The position on faith and reason that I have just sketched is not simply that of ancient or medieval Christianity. It remains, by and large, the standard position held today, with varying nuances, by Catholics, Orthodox, Anglicans, and many Protestants. Revelation is relatively necessary to know religious truths that lie within the grasp of reason and is absolutely necessary to know strict mysteries.
In the seventeenth century an alternative position was put forward in England by Lord Herbert of Cherbury (1583-1648). He maintained that revelation was unnecessary because human reason was able to know all the truths requisite for salvation. In this list he included three primary truths: the existence of God, the moral law, and retribution in a future life. God, according to Lord Herbert, had implanted in the human soul from the beginning five innate religious ideas: the existence of God, divine worship, the practice of virtue, repentance for sin, and personal immortality.
Shortly after its invention by Lord Herbert, deism received indirect support from the physics of Isaac Newton (1642-1727) and the philosophy of John Locke (1632-1704). The physical world, according to Newton, was explicable in terms of "insurmountable and uniform natural laws" that could be discovered by observation and formulated mathematically. By mastering these laws human reason could explain cosmic events that had previously been ascribed to divine intervention. The beauty and variety of the system, Newton believed, was irrefutable evidence that it had been designed and produced by an intelligent and powerful Creator. Close though he was to deism, Newton differed from the strict deists insofar as he invoked God as a special physical cause to keep the planets in stable orbits. He believed in biblical prophecies, but rejected the doctrines of the Trinity and Incarnation as irrational.
Newton's close friend John Locke, though not a deist, supplied an epistemological grounding for deism more plausible than the innatism of Lord Herbert. Beginning with human experience of the external world, he accepted a version of the argument from causality that demonstrated, as he thought, the existence of God as the uncaused Necessary Being, eternal, all-powerful, and all-knowing. Locke also believed in Christian revelation on the ground of biblical prophecies and miracles. But he held that reason should be the ultimate judge of all truth and that the firmness of our assent to any proposition should not exceed the strength of the evidence that we could produce in its favor. It followed that revealed truths, which rested on indirect proofs from reports in Scripture and tradition, were less certain than things known directly by reason. …