What does Genesis 1:3 mean?

This verse records God's first spoken words in the Bible: words of creation. God literally speaks light into existence in the universe. As used in this form, in this passage, this is meant to be understood as natural light. While aspects of Genesis chapters 1 and 2 are often debated, this is clearly not intended as a metaphor for spiritual light or something else. Before this moment, light did not exist in the physical universe (Genesis 1:2). God intends for us to understand Him as the Creator even of light itself. Without Him, there would be only darkness.

Some might object to the idea of light existing before stars or the sun. As an interesting scientific point, though, secular models such as the Big Bang themselves theorize that light—photons—actually existed before complex forms of matter. In other words, just as the Bible stated that there was "a beginning" long before secular science admitted the same, the Bible also said that light existed before stars, well in advance of secular science coming to the same conclusion.