Relatively few Christians are actually aware of the teachings of Old Earth Creationism (OEC). This article attempts to clarify it for the uninitiated. It is largely based on material from Reasons to Believe, but others have different interpretations on certain things which are worthy of consideration.
What I hope to accomplish is to show that the OEC view is entirely reasonable from a Biblical perspective, perhaps even more internally consistent within Scripture than the Young Earth Creationist (YEC) view.
Nearly all astronomers believe in the Big Bang -- the absolute beginning of all matter, energy, space, and time. Genesis 1 verse 1 lasts through most of the history of the universe, up to when the earth forms. Cosmic expansion is occurring, as attested to by the Prophets at least 10 times. This expansion and its parameters are mind-bogglingly fine-tuned. See Jeremiah 10:12c & 51:15c, God "stretched out the heavens by His understanding. Note that if any of several properties of the universe at its creation were a tiny bit different, no life of any kind would be possible at any time nor place in the universe. The LORD "created the heavens and stretched them out" (Isaiah 42:5). Time begins (Titus 1:2). The sun and stars exist, since God created the heavens "in the beginning." All this, and more, match Big Bang cosmology with amazing accuracy, and many Bible authors agree.
God then orchestrates cosmic events to cause the earth to form (Job 38:38, Psalm 104:5). It is initially in a barren, hostile state (Gen 1:2a). A super-thick atmosphere quickly forms, beginning a choking greenhouse period, blocking out all light (Gen 1:2b, Job 38:9). Oceans form and cover pretty much the whole world (Gen 1:2b, Psalm 104:6) before plate tectonics kicked in and created continents.
God created life by divine fiat over 3.8 billion years ago (Gen 1:2c). When the Spirit is "hovering over the waters," the same word is later used when God covers Israel like a mother hen, protecting it. Obviously God is doing something big here, though the text doesn't say life specifically. Note that there is evidence of complex life appearing only a few million years after the Late Heavy Bombardment, where meteor collisions would certainly have vaporized all building blocks of life. This is far less time than a naturalistic scenario allows for. There is also evidence that no prebiotic soup, essential for explaining life without God, ever existed.
Also notice the wording in Gen 1:2 -- "Now the earth was empty..." I believe this sets the frame of reference for what is to come. It is now talking about a hypothetical observer on the earth. The whole universe is no longer in view.
Note on the word DAY as used in Genesis 1: This comes from the Hebrew yom which has three possible meanings: 1) A 24 hour day. 2) The daylight portion of a day, sunrise to sunset. 3) A long but finite period of time. Young earth creationists insist that we must use the first definition. Many people, including the leading evangelical Hebrew scholar Gleason Archer, disagree and say that there is good reason to take the third definition. He argues that "there was evening, and there was morning, a second day" (and so on) are exactly not what we would expect if they were intended to be 24 hour days. Instead, he argues, it indicates the second or third definition of yom is in use. Also, the words for "evening" and "morning" simply indicate the end and the beginning of a yom, whichever definition of yom is being used in context.
Up till now, the earth was covered by darkness due to a thick atmosphere. The word for "let there be" is NOT first-time ex-nihilo Creation, but sipmly "let there appear." Remember the frame of reference, a hypothetical observer on earth's surface, which had been covered by a thick atmosphere. This is when something happens to start to dissipate the atmosphere to allow light from the sun to begin to reach the ground. It was not yet transparent, and you couldn't directly see the heavens, but light was at least there.
What happened? Almost certainly an exquisitely fine-tuned cosmic collision that eventually formed the moon out of much of our previous thick atmosphere. Had that collision not occured with extremely fine-tuned parameters, Earth never would have been suitable for life. All these had to be "just right": The size of the colliding object, its mass, its angle of impact, and its speed. This really is the dominant theory of the moon's formation, and should be considered nothing less than a miracle. As Christians, of course, we know that it was a miracle.
This is a little vague, but it seems as though God was preparing the earth for an efficient water cycle. The atmosphere of the earth was being developed in order to sustain more advanced living things.
(Psalm 104:7-9) Necessary for life, plate tectonics are almost certainly exceedingly rare in the cosmos. The Psalm says "the mountains went up, the valleys went down" -- a pretty accurate way to describe the effects of the tectonics.
The plants created on Day 3 were initially only the simplest plants as they started to be created on land. Here the fiat day interpretation (which says that the "days" of Creation really were 24 hour days where God speaks, and results follow at an unspecified time later) might have advantages over the day-age view, as actual trees and fruit don't appear until later.
Here is where the atmosphere finally becomes completely transparent, so that the sun, moon, and stars are visible. There are two interesting parts:
We start with the Cambrian Explosion about 540-500 million years ago. I have seen secular descriptions of this event that virtually match the Biblical language "the waters teem with living creatures." Before then, there were only single-celled animals and a few worms and jellyfish, but nothing with any real form. During this relatively short period of time, every single phylum (body plan) that has ever existed came into being. Since then, not a single new phylum has appeared, but many have gone extinct -- exactly NOT what evolution would expect!
Day 5 also includes most other animals, except specific ones mentioned in day 6. Remember that the Bible does not give an exhaustive account of things created, but an adequate one. Note also that the Hebrew word bara meaning creation from nothing, is used here for the animals. The Bible is not describing evolution here, but the ex-nihilo creation of something which did not previously exist. This is only the second time the word is used. (The first is for the heavens and the earth in verse 1.)
Also during this period is Psalm 104:28-30, I believe. Note that God provides for His created creatures, but when He decides, they die. He then creates (bara is used here) more animals. This is pretty consistent with the fossil record, which shows several major extinction events followed fairly shortly thereafter by an "explosion" of new, more advanced species.
This just describes some of God's more recent Creation work. The word used to form the animals here is asa, not bara. God was developing these animals, but nothing completely new appeared here. (Asa was also used for "God also made the stars" in Day 4.)
For humans, both bara and asa were used. God created something that had never before existed, a being in His image. He also formed the man from the dust, which was not in itself an ex-nihilo creation.
Then for completeness' sake, there is the one and only verse in Genesis 1 that I think is more easily understood from the YEC view, verse 30 where the animals are given "every green plant for food." This is not fatal to OEC, however. One must simply keep in mind that the Bible does not specify everything that happened. Yes, animals could eat every green plant. But the Bible does not say that no animals ever ate meat. (Just like the Bible never says it didn't rain before the Flood!) It is also telling Adam (and us) of the importance of green plants.
Day 7, God's rest. Note that it is not closed with "evening and morning, 7th day" as are the others. Combine that with Hebrews 4:1-11, saying we can still enter God's Sabbath rest, and I think we are still in the 7th day. That day will close when Christ comes back and creates the new heaven and earth!
I know this is hard for some people to swallow at first. But I urge you to give it serious consideration. (There are other variations also worthy of such.) Why is it so important? The Christian faith is based on truth. The YEC view makes a number of claims which are simply incompatible with numerous lines of evidence. If we are using false information to "prove" Christianity, what does that say about our faith, and what does that say to the rest of the world? This OEC view takes the Biblical text seriously and is compatible with everything science has discovered about the earth.
Christian geologists and astronomers are almost all old-earth. Really the only scientists who are young earth are those who started with the belief that YEC was the only reasonable literal interpretation of the Bible. I think I have shown that that simply isn't the case. In fact I really believe that the day age and/or fiat day interpretation is more consistent within Scriptures themselves, not just other evidence, than the YEC view. Sure, it's not what you (and I) were taught in Sunday School as kids, but take a closer look. I think you'll be amazed!
Learning this stuff has increased my faith in the Bible by an order of magnitude. I was amazed at the accuracy of the Bible on the subject of earth's formation, and amazed that the Big Bang requires a Creator that is uniquely described by the Bible. No other god among world religions comes close!