Adapted from Creation Answer Book by Hank Hanegraaff 

Although creation ex nihilo has been compromised, confused, and contradicted, nothing could be more certain, correct, or theologically significant. Why? Because the doctrine of creation out of nothing (ex nihilo) implies God’s necessary existence, underscores his divine freedom, and exhibits his divine omnipotence.

First, creation out of nothing bolsters the notion of God’s necessary existence as the only Being who cannot not be. As such, the church fathers described the Father of creation as uncreated and unbegotten, in contrast to all else that was created and begotten. Put another way, all that exists, except God himself, is necessarily contingent on and grounded in the creative decisions and will of God.

Furthermore, creation ex nihilo also calls attention to God’s freedom to create or to act otherwise. As such, the cosmos and all that is in it was neither mandatory nor a mishap. God freely chose to create humans and a habitat distinct from himself.

Finally, the doctrine of creation out of nothing underscores the reality that God alone is omnipotent. A God who creates out of eternally existing matter is less than the omnipotent  Sovereign of the universe who spoke, and all that is leaped into existence.

Is creation ex nihilo theologically significant? Indeed! It makes all the difference in the world.

For this is what the Lord says—
he who created the heavens,
he is God;
he who fashioned and made the earth,
he founded it;
he did not create it to be empty,
but formed it to be inhabited—
he says:
“I am the Lord<,
and there is no other.”

Isaiah 45:18


Source (and for further study), see Paul Copan and William Lane Craig, Creation Out of Nothing: A Biblical, Philosophical, and Scientific Exploration (Grand Rapids: Baker Academic, 2004).