What does the Bible say about young earth vs. old earth?

from the old testament

• In the young earth view, the Hebrew word 'yom' in Genesis 1 means ordinary 24-hour days. The repeated “evening and morning” and the pattern of six days of work followed by one day of rest are understood as pointing to normal 24-hour days (Genesis 1:5–31; Exodus 20:11).
• In the old earth view, the Hebrew word 'yom' in Genesis 1 is interpreted as long, indeterminate ages. Neither the repeated “evening and morning” in Genesis 1 nor the unique numbering scheme (day one, second day, third day, etc.) forces 'yom' to mean a 24 hour period. In the Old Testament, 'yom' often refers to a longer period. For example, in Genesis 2:4, the word day ('yom') refers to the whole creation period.
• In the young-earth view, the genealogies of Genesis 5 and 11 are read as a continuous timeline. Adding the ages in Genesis 5 and 11, along with other biblical genealogies, places the creation 6,000-10,000 years ago.
• In the old earth view, the genealogies of Genesis 5 and 11 are not necessarily complete timelines. Biblical genealogies sometimes skip generations, so the lists in Genesis 5 and 11 may not allow us to calculate the earth’s age with certainty.
• Creation reveals God's glory and the work of His hands (Psalm 19:1). Our worship should be directed to God, rather than to any part of His creation (Romans 1:25).

from the new testament

• Jesus and Paul connect Adam, sin, death, and redemption (Matthew 19:4–6; Romans 5:12–19; 1 Corinthians 15:21–22, 45). Both young-earth and old-earth creationists treat Adam and Eve as real historical people (no evolution involved). Romans 5:12-15 clearly teaches that Adam was one real, historical man, not a symbol.
• In the young earth view, all death, including the death of animals, comes from the sin of Adam and Eve. In this view, Romans 5:12a teaches that "sin came into the world through one man, and death through sin." Accordingly, the world of Genesis 1 was different from our world in that God did not create any carnivorous animals in Genesis 1. Death and decay began after the Fall (Genesis 3:14-24).
• In the old earth view, carnivorous animals and thus animal death existed before the Fall. The same animals we see today, including carnivorous animals, existed in Genesis 1 and 2. The Bible does not indicate that God created new animal kinds after the Fall, nor was there any radical change to the body plans of the existing kinds. In this view, Romans 5:12b goes on to say: "so death spread to all men because all sinned." This passage, and the surrounding context, does not mean animal death, but refers to the death of humans and spiritual separation.

implications for today

Is the earth young or old? Were the creation days 24 hours, or long ages, or God's workdays? Even in the 4th century, Augustine, in his classic work "The City of God," confessed that he did not find the days of Genesis 1 easy to understand. Augustine said: "What kind of days these are is difficult or impossible to imagine, to say nothing of describing them... We cannot understand what happened as it is presented to us; and yet we must believe it without hesitation." Not much has changed since Augustine.

The Bible does not explicitly state the age of the earth; therefore, it is not an essential doctrine of the faith. The age of the earth should not divide believers. Faithful Christians disagree on how to interpret Genesis 1, so it is wise to hold the earth’s age with humility while keeping the central biblical truth in view: God created the world, humanity bears his image, sin is real, and redemption comes through Jesus Christ.