A person’s belief of the age of the earth reflects a belief system. Priority is given to either the claims of science or the claims of the Bible. The age of the earth matters for the Christian because of what the Bible says about the origin of the earth, of humanity and of suffering. If the Bible is not historically accurate about the age of the earth then it’s reliability regarding the sin of man is suspect.
The inclusion of a long period of time before the creation week recorded in Genesis 1 does great damage to the literal reading of Genesis 1-3. An earth populated with animals for millions of years before the creation week presents significant theological problems concerning death, decay and destruction. If the fossil record is the record of an ancient earth that existed before Adam and Eve, then death and disease were common before the events recorded in Genesis 3. If death existed before sin, then death is not the punishment of sin. If suffering existed before the creation of man, then suffering is not a consequence of sin.
If the earth is millions or billions of years old, there is much in earth’s history that is not revealed in the Bible. While the Bible never attempts to present a full history of all mankind- it does not contain the history of China, Greenland or South America the Bible does present a history of the origin of the world, the formation of humans and the spread of sin. If the Bible leaves out huge gulfs of time, there is abundant space to question the reliability of the Bible for understanding the nature of humanity. If the historical record of the Bible has major gaps, then that calls into question the BIble as a valid historical record. This matters because sin, salvation and the promises of God are connected to a historical context. Jesus is a historical figure whose history is traced from person to person all the way back to a historical Adam. If the Bible is not reliable as a history book, does it present an accurate historical picture of Jesus?
This question matters because it shapes how a person reads the Bible. If the Bible is a reliable historical record, then great weight will be placed upon its genealogies and historical markers. If the Bible is not to be read literally, or if its history is a series of homilies intended to teach spiritual truths, then the chronological data in the Bible will have little importance in the discussion of the age of the earth. This question matters because the inclusion of millions of years into the history of man undermines the reliability of the Bible when it discusses the origins of sin and suffering. If the Bible cannot be trusted as an accurate historical record of the earliest days of man, can it be trusted when it discusses Abraham and Moses, Israel, Babylon, the Roman Empire, the apostles or Jesus? If the Bible does not present in Genesis an accurate, literal record of the history of the world, when does it begin to do so? If the Bible is not trustworthy to teach of how man sinned, how can it be trustworthy to teach how man is saved?