Biological macroevolution is a scientific theory aimed at explaining the origin of species. Many Christian scholars after Darwin asked if biological macroevolution is compatible with the Christian faith. Those who answered in a positive way never challenged the theory itself. Instead, they came up with the idea that God used evolution to produce species. Evolution was called a secondary cause of creation: As a carpenter uses saw and hammer to make a bench, God uses evolution to create biodiversity. Those scholars often distinguish between the mechanism of evolution and the effects in the form of different species. They say that the mechanism may change, in fact there may be even many different mechanisms of evolution, but the grand evolutionary claims about universal common ancestry and natural transformation of species are valid regardless of any mechanism. In this sense biological macroevolution becomes theistic evolution, that is, the theological concept saying that God did not create species separately but instead used the powers of nature (such as generation, random variation and natural selection) to bring about the whole diversity of life. In theistic evolution there is room for God—He is considered the highest Being who acts as the final cause of the evolutionary process. Theistic evolutionists claim to be radically different from atheistic evolutionists who deny any higher cause or any finality in evolution. However, theistic evolutionists agree with atheists that there are no marks of divine causality left in the natural order. Consequently, the science of biology can fully explain the origin of species. Thomistic evolutionists say the same as the theistic evolutionists, with the addition that theistic evolution is compatible with Thomistic philosophy. According to Thomists (i.e., those Thomists who support theistic evolution), had Aquinas known modern science he would not have a problem with admitting the three grand claims of biological macroevolution: universal common ancestry, transformation of species, and the natural origin of species.