Modern Western thought includes several perspectives on the origins of the universe and of life. Religious literalism may hold with a Six Day Creation occurring about 6000 BC, with each twenty-four hour day's developments being a new product of God's spoken word. Theistic evolutionism blends acceptance of scientific evidence of long-term developments in plant and animal species over spans of millions of years with acceptance of a Creator God who triggered and guided the development of the universe and the life it contains.

Agnostic and atheistic evolutionary views accept scientific evidence of long-term developments in the genera and species of prehistoric and presentday life, differing on the issue of whether the existence or nonexistence of God is unknowable, or that God simply does not exist.

Within the varieties of evolutionary thought, still another issue lurks: that of gradualism versus cataclysm in evolution. Gradualist thought holds that the...