Natural theologians explained the properties of nature theologically (i.e. by direct action of God). They were highly influential from the 18th century until Darwin.
Important thinkers of this type:
• John Ray
• William Paley
Darwin himself was much influenced by the examples of adaptation, such as the vertebrate eye, discussed by Paley. Paley explained adaptation in nature by the creative action of God: when God miraculously created the world and its living creatures, he/she miraculously created their adaptations too.
The key difference between natural theology and Darwinism:
Natural theology explains adaptation by supernatural action, and Darwinism explains it by natural selection.
This image opposite is of a mantid, wonderfully adapted to its environment. Natural theology and Darwinism disagree in how to explain this.