Charles Darwin introduced his General Theory of Evolution (GTE) as an alternative to popular Western ideas of Christianity. In this biological sense, the "General Theory of Evolution" includes two major tenets or axioms, both of which are unfalsifiable (meaning they are not capable of being tested): Abiogenesis and Common Descent. Although scientific methods are used to promote both belief and disbelief in these two concepts, the concepts themselves are outside operational science: As axioms, they cannot be proven or disprove; axioms are foundational, unquestioned by supporters.