By what means did God accomplish the feat of creation ex nihilo? By His speech. Augustine called this the divine imperative or fiat. God spoke the words “Let there be” (Gen. 1:3, 6, 14)—meaning “There must be”—and things appeared. In the film Anna and the King of Siam, the king frequently says, “So let it be said; so let it be done.” That is an imperial command that cannot be countermanded. In creation, there was no block of stone or mass of unstructured matter, but only the command of God, who alone had the power to make things happen simply by uttering a command. It was the power of His word that created.
Until the Enlightenment, the most firmly established article of Christian faith in the secular world was that of creation. It had been established not only by revelation but also by reason, not only by religion but also by science. To medieval philosophers, the idea of something coming from nothing was absurd, unscientific, and illogical. If something exists, it must either have the power of being in itself or it must come from something that has the power of being in itself. Otherwise, nothing at all could exist. This point is important because atheists and secularists in recent centuries have focused their attention on creation. If they can undermine our certainty that we live in a created universe, they can undermine any argument for the existence of God. If you do away with creation, you do away with the Creator.
The classic Christian doctrine of creation is creation ex nihilo (out of nothing). The writer who most thoroughly developed this concept was Augustine. He said God spoke the universe into being out of nothing. God did not take eternally preexisting matter or substance and reshape or reconfigure it into the present world. His creative activity is not like that of human artists.
Think of Michelangelo, who sculpted magnificent statues from stone. Michelangelo believed that he did not create a statue but released the figure from its stone prison. It is inconceivable that his statues could have created themselves without the work of a master sculptor. Michelangelo’s genius was his unique ability to reshape a block of stone into a magnificent figure. But he had to start with some substance or material. Similarly, Rembrandt had to begin with his canvas and paints. His inventive brilliance was in working with materials already at his disposal. We call this creativity, but no one in this world has the power or ability to create something out of nothing. Only God can do that.
When we assert creation ex nihilo, the obvious question is, How could God possibly do such a thing? It almost sounds like magic, where God is the magician who pulls a rabbit out of a hat. But in the act of creation, there were no trick mirrors, no rabbits, no hats, and not even a magic wand. Every effect must have a cause. There are different kinds of causes. Aristotle, for example, differentiated between several kinds, using the example of a sculpture: its material cause (out of which something comes) is the block of stone; its instrumental cause (the means by which the effect is brought to pass) is the chisel and hammer, instruments the sculptor uses to bring about the effect.