What does Genesis 1:5 mean?

Genesis is a book of firsts. In verse 3, we heard God's first recorded words in the Bible: "Let there be light." We saw God's first approval of something as "good." Now, in verse 5, we see God name something for the first time.

God named the light day and the darkness "night." Naming things is a significant act in the book of Genesis, as well as in the rest of the Bible. Naming something, in the ancient mindset, is a claim to ownership. Having the right to name something means claiming sovereignty over that thing. Later, God will task Adam to name the animals as part of his human work in ruling and subduing the earth.

In part, then, we see that God means to remain Lord over night and day. He created them. He intended for day and night to exist; they are not merely an accidental consequence of the natural world. Another way to apply this point is that God is not merely creating and then allowing this creation to spin out of control. What He has created, He still maintains authority over.

Finally, the verse ends with the blueprint used for the description of each of the six days of creation: There was evening and there was morning, the first day. From very early on, the people of Israel thought of a day as beginning in the evening, at sunset, and continuing until the sun set on the following day. That may explain the wording in Genesis 1 of "evening and morning."

Some scholars suggested that these days need not have been strict 24 hour days in the sense that we think of them. As noted before, there is nothing explicit in the text to dispute or support this claim. Nor is there anything which explicitly proves or disproves that they are most certainly 24-hour days. The God who is capable of speaking light into the world is certainly capable of creating as much as He would choose to in a 24-hour period of time, or of creating using a longer process. The important details are those which God has actually given: He created light, and called it "good."