This question has stoked controversy among conservative Christians in recent times, but it has proved to be of little interest to theistic evolutionists (those who accept evolution as God’s mechanism in creation) and those rejecting Genesis as God’s inerrant Word. The debate has been primarily between young- and old earth creationists, who believe that God literally created the various kinds of living things (as opposed to the common descent of Darwinism). Both sides hold that humans have not descended from other species, and both reject the atheism and macroevolutionary theory of neo-Darwinism.
The two creationist camps, however, differ in interpreting the creation days of Genesis. If the days were consecutive 24-hour periods, and if the earth was created on the first day, then calculations based on biblical genealogies reveal that the earth was created only thousands of years ago. If the days were either of indeterminate length or nonconsecutive, then the Bible does not reveal when the earth was created. Interestingly, both sides agree that the genealogies reveal that Adam and Eve were specially created only thousands of years ago.
Young earth creationists (YCs) interpret the days as 24-hour, consecutive periods for reasons such as the following: (1) The days in Gn 1 are consecutively numbered and comprised of an “evening and morning.” (2) Exodus 20:8-11 commands a literal week of six days of work and one day of rest based on God’s original creation/rest week. The two weeks would seem, then, to be of equal duration. (3) According to Rm 5:12, “sin entered the world through one man, and death through sin,” but old-earth creationism would have animal death entering the world before the sin of Adam and Eve.
Old earth creationists (OCs) argue against 24-hour creation days for reasons such as these: (1) The Hebrew word for “day” (yom) is used in different ways in the creation account. For instance, Gn 1:5 refers yom only to daytime (daylight), not nighttime. Also, Gn 2:4, literally translated, speaks of “the yom that the LORD God made the earth and the heavens.” (2) God’s rest on the seventh “day” has no evening and morning (Gn 2:2-3), and Heb 4:3-11 portrays this same Sabbath as continuing to the present time. (3) Adam could not have named all the birds and animals in 24 hours according to Gn 2.
Both sides believe they have strong arguments favoring their interpretation and rebutting the other side. And historically, debate regarding biblical interpretation has often led to a clearer understanding of God’s Word. But it is also highly debatable whether this issue merits the rancor and division often attending it. Some YCs accuse OCs of compromising the Bible with evolutionary science. Some OCs charge YCs with undermining biblical credibility by generating a false conflict between science and the Scriptures.
Happily, one thing is not debatable among those who believe the Bible: even if the correct interpretation of the creation days is not readily apparent in the present generation, the Bible can be trusted in every way. Debates about biblical interpretations should not be interpreted as the failure of Holy Scripture.