In Collins’s explanation, “one who would say that the knowledge of God’s existence simply cannot be achieved” (168). The term was coined in 1869 by the British scientist Thomas Henry Huxley from the Greek for “not to know.”

The idea that the universe seems precisely tuned to give rise to intelligent life (human beings). Discussed in Chapter 4: “The Origins of the Universe.”

The argument that the “irreducible complexity” of the universe and living organisms proves that they must have had a designer, i.e., God. Also known as an “argument from personal incredulity” (186), because its original formulation by the 19th-century naturalist William Paley expressed disbelief that such a world could have come about by chance. Collins cautions that incredulity in the face of a complex universe does not prove God’s existence; science is constantly discovering naturalistic explanations for things formerly considered too complex to understand.