This question can be answered by going back to the original language that Genesis was written in: Hebrew. The Hebrew word for “day” in Genesis Chapter 1 is “yom” (Strong’s #3117). We know that in English, day can have multiple meanings even in the same sentence. For example “Back in my father’s day, it took 12 days to cross the country in a day.” Each “day” means a different time frame that we can understand from the context. So let’s apply that to Genesis using the Strong’s concordance. When “yom” is used in Genesis to describe each day, it is used along with the phrase “evening and morning” along with an ordinal number (1, 2, 3, etc.). Adding these three qualifiers to the word “yom” insists that it means a literal, 24-hour day. This is what we find in Genesis chapter 1. So we can conclude that God created the world and everything in it in six 24 hours days, and rested on the seventh. God could have done it in six minutes, six years, or in one second, but what we have written is six literal days.
The word “yom” is used 2301 times in the Old Testament. Outside of Genesis, “yom” is used with an ordinal number 410 times. The phrase “evening and morning” is used with “yom” 38 times. “Yom” plus either “evening” or “morning” is used 23 times. “Yom” plus the word “night” is used 52 times. Every time “yom” is used as mentioned above, it always implies a literal, 24-hour day.
Why is it that Genesis is questioned so much about the length of a day? Why not question how long Jonah was in the great fish? Was he in there for 3 days or 3 thousand years? How many days did Joshua march around Jericho? Seven days or seven thousand years? It doesn’t make sense any other way. Some in the church try to interpret the “day” as a long period of time, and by doing so allowing time for evolution to take place and thus agree with secular science that claims the world is billions of years old. This simply cannot be done when you apply the word to the context. Context is very important when interpreting Scripture, a child’s book, or the newspaper.
Take this time to thank God for clearly telling us in His Word how this world and everything in it came to be. It all starts with Genesis.