Featured in the newest Dialogue Magazine »

German astronomer and mathematician Johann Kepler (1571 –1630) was a central figure in the 17th century scientific revolution. He was not only the founder of the physical astronomy discipline, “the first astrophysist,” and an outstanding scientist, he was also a committed Christian (Morris, 1998, p. 33; Gingerich, 1993, p. 305). Kepler is best known for discovering the three laws of planetary motion that provided a foundation for Isaac Newton’s theory of universal gravitation (Dao, 2008, p. 8). The problem that motivated the discovery of his three laws was observational astronomy did not support the circular orbit belief, and Kepler was able to determine why.

The first law named after him is that planets travel in elliptical paths and not perfect circular orbits as commonly believed. Kepler’s second law states that planets sweep out equal areas in equal times, producing an elliptical orbit (Sagan, 1980, p. 62). His third law is that the square of the periodic times are proportional to the cubes of their mean distance from the sun (Dampier, 1949, p. 128). Although the third law is only roughly true, and the discovery of new planets has rendered it of little use today, it was an important step in achieving the insight about the planets that we have today.

The three laws were not his only major scientific contribution to science. He also completed fundamental scientific work in the field of optics, having invented an improved version of the refracting telescope that today is called the Keplerian Telescope. His telescopic discoveries were critical in helping Galileo Galilei overthrow the view that the sun circles the earth, called the geocentric worldview.

Inspired by His Biblical Faith

Kepler believed that God was the creator of the Cosmos, and his lifelong goal was “to learn the eschatology of the world,” and to do this he “dared to contemplate the Mind of God” (Sagan, 1980, p. 56). This goal “became a lifelong obsession,” and the hubristic longings of Kepler “were to carry Europe out of the cloister of medieval thought,” and into the modern scientific age (Sagan, 1980, p. 56). Furthermore, Kepler believed that his study of the solar system allowed him to glimpse the “image of perfection and cosmic glory” of the universe. He was searching for “ultimate causes, the mathematical harmonies in the mind of the Creator” (Dampier, 1949, p. 127). Kepler later wrote that geometry “is co-eternal with the mind of God” because it provided God with a model for the Creation … If the world was crafted by God, should it not be examined closely? Was not all of creation an expression of the harmonies in the mind of God? The book of Nature had waited more than a millennium for a reader (Sagan, 1980, p. 56).

That reader, Sagan noted, was Kepler himself.

After studying both the Ptolemaic and the Copernican models of planetary motion, Kepler concluded that the evidence favored the Copernican system (Donahue, 1982). As a student, he defended heliocentrism from both the theoretical and theological perspectives, maintaining that the Sun was the principal source of the force that holds the solar system together.

His original goal to become a minister was never fulfilled (Dao, 2008, p. 8). However, Kepler was eventually able to obtain a position teaching mathematics and astronomy at the Protestant school in Graz, Austria. He later became an assistant to the famous astronomer, Tycho Brahe, and eventually was appointed the empirical mathematician to Emperor Rudolf II.

Kepler was evidently the first scientist to proclaim that his astronomical research was merely “‘thinking God’s thoughts after Him,’ a motto adopted by many believing scientists since his time” (Morris, 1998, p.13). Kepler also wrote: “Since we astronomers are priests of the highest God in regard to the book of nature, it befits us to be thoughtful, not of the glory of our minds, but rather, above all else, of the glory of God” (Morris, 1998, p.13). Furthermore, Kepler’s astronomical research also involved the study of Biblical chronology, concluding that “the world was created about 7,000 years ago” (Morris, 1998, p. 13).


Although his conclusions garnered much opposition at first, in the end he “stayed true to his faith … and his scientific discoveries would eventually win him acclaim, legitimize the discoveries of his contemporary Galileo, and serve as a major influence on the scientists who came after him” (Dao, 2008, p. 8). As Harvard astronomer Owen Gingerich noted, Kepler’s gifts were so great that “any assessment of this man’s genius must be incomplete and imperfect” (1993, p. 305). An impressive monument to him exists in Germany, and his home has been preserved as a tourist site (Love, 2015, pp. 189-190). Let us never forget Johann Kepler, an exemplary scientist and Christian.


Dampier, Sir William. 1949. A History of Science. New York: Cambridge University Press. Fourth edition.

Dao, Christine. 2008. “Man of science, man of God: Johann Kepler” 2008. Acts & Facts 37(3): 8 March.

Donahue, William. 1982. “A Novelist’s Kepler,” Journal for the History of Astronomy, 13:135–136.

Gingerich, Owen. 1993. The Eye of Heaven: Ptolemy, Copernicus, Kepler. New York, NY: American Institute of Physics.

Lamont, Ann. 1992. Outstanding scientist and committed Christian” Creation Ex Nihilo 15(1): 40-43, December.

Love, David K. 2015. Kepler and the Universe: How One Man Revolutionized Astronomy. Amherst, NY: Prometheus Books.

Morris, Henry M. 1998. Men of Science/Men of God: Great Scientists Who Believed the Bible. Green Forest, AR: Master Books. Fourteenth printing.

Sagan, Carl. 1980. Cosmos. New York: Random House.

Jerry Bergman
June 2016

Subscribe to Dialogue