Religious faith provides a strong motivation for mobilizing many geoscientists in making the world both a safer place to live and one in which a sustainable use of resources could be developed for the future. The history of science up to the present day is rich in individuals who have seen their scientific endeavors as a natural outworking of their faith. This is unsurprising, for scientists in many/most religious traditions are keenly aware of the interface among the creator (God), his creation (“nature”), and his creatures (humankind). Many of the most pressing problems of our day can be addressed by geoscientists; these include global climate change, water resources, mineral resources, and disasters such as floods, volcanic eruptions, and earthquakes. In addition, many religious folk are willing to support relief and development work in low-income areas both near and far from home, and they are educated and motivated to do so by common links of religious affiliations that cut across national and cultural boundaries and are global in scope.

Nicholas Steno (1638–1686) always started from his own observations, either in anatomy and geology or regarding theological truths. This was in line with Galileo Galilei’s principle that when investigating physical questions, one should not begin with biblical texts. Thus, Steno had an advantage over other theologians like Vincent de Contenson (1641–1674) who adopted old-fashioned scientific theories from classical antiquity. Though Steno’s conception, in contrast to Athanasius Kircher (1601–1680), emphasized the accidental nature of Earth’s history, it still left a place for the Creator. When observing the geological structure of Earth, Steno concluded that shifts of Earth’s surface were part of nature’s corruption by the original sin of mankind, referring to biblical Adam and Eve, Genesis 3:1–24. Therefore, Steno, who was the first to present a history of Earth before the Deluge, viewed subterranean veins as places not created by God at the beginning of time, but instead within a geological process having begun with the malediction of Earth; in other words, nature was disturbed by original sin. For him, God’s original purpose for Earth’s properties remained hidden and unknown to men, because most of them at first glance seemed to be useless for life on Earth. Both before and after Steno’s conversion, his standpoint remained fundamentally the same and supported his own geological insights.

Steno’s life was punctuated by two conversions: (1) from anatomy and medicine to geology, and (2) from Lutheran to Roman Catholic confession. Why was Steno (1638–1686) motivated to solve geological problems soon after he entered the Tuscan region of Italy? Was there any link between his scientific conversion and the religious one, which occurred almost simultaneously and produced a revolution in his life? The origin of marine fossils found in mountains had been debated in Italy for one and a half centuries. Leonardo da Vinci (1452–1519) had already given a modern scientific explanation for the problem. Ulisse Aldrovandi (1522–1605) later tackled the problem with an experimental-taxonomic approach (his famous museum and studio), and it was he who coined the word “geology” in 1603. Italy provided spectacular exposures of rocky outcrops that must have impressed the Danish scientist who had lived in the forested north European lowlands. Since the time of Giotto and his successors, such as Mantegna, Pollaiolo, Leonardo, and Bellini, the imposing Italian landscape had stimulated the visualization of geology. Inevitably, science and art merged perfectly in the work of painter and paleontologist Agostino Scilla (1629–1700). Steno was methodologically skilled and intellectually curious and was thus open to the stimuli that Italy had to offer in order to unwittingly rediscover, after Leonardo, the principles of geology and to solve the problem of fossils. Steno’s inclination to detailed “anatomical” observation of natural objects and processes as well as his religious conversion were influenced by his acquaintance with the circle of Galileo Galilei’s (1564–1647) disciples who formed the Accademia del Cimento. They were firm Roman Catholic believers. To the inductive mild rationalist and open-minded Steno, this connection could not be dismissed, and it prepared him for changing his paradigms for the sake of consistency. This occurred when a Corpus Domini procession triggered a revelation and led to his religious conversion.

In the eighteenth century, many Europeans and Americans embraced a world-view in which the natural world was seen as complete, full, and perfect, as created by God. Within this worldview, no species ever became extinct because such an event would destroy the perfection of nature. Toward the end of the eighteenth century, the concept that no species had ever become extinct was increasingly challenged by evidence from the fossil record. By the early nineteenth century, a new paradigm, the “former-worlds” view of Earth history, began to emerge. Buffon had argued that New World quadrupeds were degenerate varieties of Old World species, and that at least one of them had gone extinct. The idea of New World degeneracy thus became connected with the concept of extinction. Thomas Jefferson conducted a long, personal campaign to discredit these ideas of Buffon’s, arguing against them in the early 1780s in Notes on the State of Virginia and also in his 1797 Megalonyx memoir. Jefferson resisted the concept of extinction for a very long time, and he was never able to let go of his “completeness-of-nature” worldview. I suggest that several factors contributed to Jefferson’s inability to relinquish his worldview, in spite of the fact that there was considerable empirical evidence showing that it was not valid. The most influential factors were (1) Jefferson’s emotional and public commitment to the completeness-of-nature worldview, and (2) Jefferson’s personality traits, which were acquired in part through his experiences as an eldest son.

It is widely recognized that Darwin discredited the argument from design for the existence of God. Less well known is the history of a related notion, the argument from law, according to which there cannot be a law without a legislator. Both rested upon the more fundamental assumption that we can interpret the world on the basis of privileged knowledge of God, supposedly an anthropomorphic one. Given that the same being both created the universe and ordained the laws of nature that govern it, viewing geological history and the fossil record as teleological is much easier. Pre-Darwinian scientists invoked both design and law in explaining the history of the world. In either case, the result was a tendency to view the fossil record as if it were, like a developing embryo, headed in a particular direction. Those who have attempted to salvage that view in the face of Darwin’s contribution have generally put more of a causal burden upon laws of nature. Even though that may seem more “scientific,” both arguments are grounded in mysticism.