On some topics, the Bible is extremely clear. For example, our moral obligations toward God and the method of salvation are discussed in detail. On other topics, however, the Bible doesn’t provide nearly as much information. Reading the Scriptures carefully, one finds that the more critical a topic is, the more directly the Bible addresses it. In other words, “the main things are the plain things.” One of the topics not explicitly addressed in Scripture is the age of the earth.
There are several ways of attempting to determine the age of the earth. Every method relies on certain assumptions which may or may not be accurate. All fall in a spectrum between biblical literalism and scientific literalism.
One method of determining the age of the earth assumes that the six days of creation presented in Genesis 1 were literal 24-hour periods and that there are no gaps in the chronology or genealogy of Genesis. The years listed in the genealogies of Genesis are then added to get an approximate time from creation to certain Old Testament figures. Using this method, we arrive at an age for Earth of approximately 6,000 years. This was first proffered by Archbishop James Ussher who published in 1654 a work, where he calculated the date of the Creation to have been nightfall on 22 October 4004 BC.
It’s important to realize that the Bible nowhere explicitly states the age of the earth—this is a calculated number. There is a difference between the date of the earth and mankind, the date of the planet is much older than that of mankind.
Another method of determining the age of the earth is to use resources such as radiometric (carbon) dating, geologic cycles, and so forth. By comparing different methods, and seeing if they align, scientists attempt to determine how old the planet is. This is the method used to arrive at an age for Earth of about 4 to 5 billion years. It’s important to realize that there is no means to directly measure the age of the earth—this is also a calculated number.
Both of these methods of determining the age of the earth have potential drawbacks. There are theologians who do not believe that the Bible’s text requires the creation days to be literal 24-hour periods. Likewise, there are reasons to believe that the genealogies of Genesis have intentional gaps, only mentioning certain men in the lineage. Objective measures of the age of Earth do not seem to support it being as young as 6,000 years, and denying such evidence requires the suggestion that God made virtually every aspect of the universe “appear” to be old, for some reason. Despite claims to the contrary, many Christians who hold to an old earth view take the Bible to be infallible and inspired, but they differ on the proper interpretation of a select few verses.
On the other hand, radiometric dating is only useful or accurate back to a certain point, far less than the scale involved in dating the earth. Geologic time scales, fossil records, and so forth are highly dependent on assumptions and subject to modeling errors. The same is true of observations of the greater universe; we can only see a tiny fraction of all that exists, we can roughly see 4 % of the known universe and much of what we “know” is theoretical. In short, there are ample reasons to believe that secular estimates for the age of the earth are inaccurate, as well. Relying on science to answer scientific questions is fine, but science cannot be treated as infallible, as a practical matter science is a reactionary exercise, we predominately learn about things that have already happened.
In the end, the chronological age of the earth cannot be proven. Unfortunately, there are voices on both sides of the issue who claim theirs is the only possible interpretation—theologically or scientifically. In truth, there is no irreconcilable theological contradiction between Christianity and an old earth. Nor is there a true scientific contradiction in a young earth. Those who claim otherwise are creating division where none needs exist. Whichever view a person holds, what matters is whether or not he is trusting in God’s Word to be true and authoritative.
Topics such as the age of the earth are why Paul urged believers not to cause strife over things not detailed in the Bible (Romans 14:1–10; Titus 3:9). The age of the earth is not “plain” in the Scriptures. It is also not “main,” in that one’s view of Earth’s age has no necessary implications for one’s view of sin, salvation, morality, heaven, or hell. We can know much about who created, why He created, and how we are meant to relate to Him, but the Bible does not tell us in unambiguous terms exactly when He created.