When it comes to the various interpretations of biblical creationism, I was in the "undecided" category for many of my 32 years as a Christian. I don't know that I was ever a true Young Earth Creationist (YEC) to begin with. I read YEC articles along with Old Earth Creationist (OEC) articles every week. And while the YEC articles can be interesting and even thoughtful, I haven't been persuaded that the universe is only 6,000-10,000 years old.
I've read theories that YECers have advocated for a young earth amidst a universe billions of light years in diameter, but they are just theories. No YEC theory I've read to date has held up to scrutiny. It's one thing to say that God could do something. It's another thing altogether to be able to say that he did do something. It's what God actually did that escapes YEC's grasp because it is undiscoverable. It seems to me that much of YEC's arguments for proving a young age for the universe are undiscoverable because they also happen to be unreal. I don't mean this in an insulting way. It just seems that all of the major theories about distant starlight don't stand up to scrutiny.
My purpose today is not to present a list of detailed reasons why I've gone, "Old Earth." You can find that information elsewhere. Rather, I'd like to give three general areas of thought that have persuaded me.
There are three areas of thought that bring me to the conclusion that the universe and the earth are billions of years old: (1) The Science, (2) Bad Theology, and (3) Natural Theology.
Without a doubt, the biggest area of science to persuade me about the age of the universe has come from the distant starlight problem. If light travels through a vacuum at 186,000 miles per second, and the observable universe is 13.8 billion light years in any given direction, then the age of the universe must at least be that.
Some YEC proponents have posited theories like time running faster, light created in transit, a faster speed for light in the past, and white hole cosmology as potential solutions to the distant starlight problem. But none of them have held up as a valid explanation for the breadth of the universe with a young age of only thousands of years. With the failure of these theories we are only left with what we can observe to be true. And what we observe is that the universe is old, and not just old, but ancient.
The observable universe is estimated to be over 92 billion light years in diameter (see here). But some scientists estimate that the universe is actually much larger than we have the ability to see, as much as 250 times greater (23 trillion light years). Because of the accelerating expansion of the universe, there are some parts of the universe so far away and continuing to expand faster than light, that their light can never reach the earth to be observed and will therefore remain unseen by man, forever. This is staggering.
Another reason why I subscribe to an old earth is the consistent behavior of the laws of physics throughout the universe. In YEC theory the earth was created first and given special attention in how it was crafted. Then on the fourth day of creation all of the other stars, and presumably their planets were created. Yet, when we look at other stars and planets, the same forces that were at work on earth to create certain features and govern our motion around the sun are identical to what we can perceive elsewhere in the universe. Thus, the consistent way the laws of physics work everywhere in the universe, even for galaxies millions or billions of light years away tells me that the earth was formed under, and operates under the same laws we see elsewhere. Planet formation, star formation, gravity, speed of light, etc., are all uniform with what we also see in our solar system, and on earth. This, to me, is consistent with Genesis 1:1, "In the beginning God created the heavens and the earth." I think this is a blanket statement of what God did at the first, not a literary introduction. God created the universe, then he proceeded over time to fashion the earth for habitation (Isaiah 45:18).
The Bible doesn't say the earth is billions of years old, but neither does it say it is thousands of years old. This is something that has been forced upon the text. Therefore, we are free to deduce the earth's age from scientific observations.
YEC's position on death at the beginning of creation doesn't seem defensible to me. The YEC position is that all death is the result of the fall of man into sin. There is one sense in which this is true. God warned Adam that if he ate of the Tree of Knowledge he would die (Genesis 2:17). YEC applies this pronouncement to all of creation. Yet, I don't think the text says this. God was simply addressing Adam and Eve. He said they would die, not that everything else would die. I think this is because of one reason: other things could already die.
There is no doubt that there was death in the initial creation. But there is a difference between death in a general sense and death for sin. Adam and Even suffered death for sin. But general death already existed. If Adam peeled a banana and threw away the peel, it would die (and so would the banana upon consumption). If a bear fell off a high cliff, surely it would die. If Adam were to chop down a tree for firewood, the tree would die.
God built a creation where the possibility of death was built into the system. YEC believes that creation could not be "good" if that was so. Yet, I think YEC confuses the difference between moral good and functional good. Being built into the system, death served a good purpose, functionally speaking. This is even true in our own age. Capital punishment, as an example, is not defined by the Bible as a sin. It is a functional good for the protection of society. Killing the enemy in war is not a sin, but it serves a functional good of defense. Killing to eat is a functional good. In the days of the Mosaic Law animal sacrifice for sin was a functional good and not taken as a sin. So, even in our own sinful age we can see that certain acts of death serve a functionally good purpose. The same was true with the original creation. There was death that served a function, but not death for sin until Adam and Eve violated the law and introduced us to a different kind of death—death for sin.
I agree with Hugh Ross's point that nature tells us equal truth along with the Bible, but in a different sphere. Since the Bible doesn't tell us, directly, how old the universe is, we are free to let science deduce that, then we should go back to the scriptures to see how that natural revelation gives us insight in biblical interpretation.
Some argue that we should not let astronomy or physics help us make interpretive choices in the scripture. But I think this is inconsistent with how we treat the Bible and other sciences. We faithfully exegete the scripture while using outside discoveries to help our interpretation all the time.
We understand the meaning of certain things in Genesis because of what we have learned from archeology about Ancient Near East (ANE) culture. History and geography helps us understand the letters to the seven churches in Revelation and Paul's missionary journeys. Archeology gives us insight into legal practices of Old Testament times. Why should other sciences, like astronomy and physics, not bring the same benefits to our understanding of the scripture?
I am not arguing for defining scripture's meaning completely by outside influence. Rather, I'm arguing that these various sciences have aided our understanding of scripture and help us recognize the divine authorship and authority the text has. All sciences, whether historical, observational, or experimental, can aid our understanding of scripture without the scripture being demeaned or becoming subject to misapplication of the sciences.
I don't have the time to write out all the various discoveries that have persuaded me about the ancient nature of the universe, or to give more detail about the things I've cited here. There are more than enough online websites, articles, debates, and books available so that anyone can make this discovery themselves. Suffice it to say, I think the age of the universe is ancient in the extreme and I don't think it conflicts with a properly interpreted view of scripture. In fact, I think that my fear of God has been helped in this process. In an ancient universe I can deduce God's patience, his creativity, and his love. Because in the billions of years he has waited and planned our creation, he has patiently executed his plans, demonstrated his incredible power over vast distances and time, then he focused all of his redemptive energies on us, right here, on this little spec of cosmic dust. That is incredible beyond my imagining. And these are things of which I think a YEC view of creation misses the mark.