An old earth creationist is not a theistic evolutionist. Often these positions are equated; however, this paper is written from a non-evolutionist perspective. It is the position of this paper that viewing the "days" of Genesis 1 as epochs/eras is a better interpretative option than viewing them as 24-hour-periods based on a grammatical-literal interpretation of God's Word. The following is a cursory argument for this interpretation of Genesis 1-2.
First, it is important to affirm that the Bible teaches that creation is a valid source of truth (cf. Job 10:8-14, Ps 8, Ps. 98:2-3, Ps. 104, Hab. 3:3, Acts 7:24-31, Rom 1:18-25, Col 1:23). Therefore, one cannot discount scientific evidence. It must be carefully considered; however, it ought not to be the determining factor in our exegetical conclusions. Having said that, I think that the biblical evidence alone provides an extremely compelling case for an old-earth scenario:
1. Hebrew grammar and semantics
There are 3 literal meanings for the Hebrew word yom: (1) a literal day, (2) a 12-hour period from sunrise to sunset, and (3) an epoch, era, or longer period of time. The Hebrew word for day functions much like the English word “day”: “day” can mean 24 hours, daytime, or an unspecified period of time (i.e. "back in the day"). So, how do we determine what sense the word is being used in Genesis 1-2? The context provides us with some clues. In the context of Genesis 1-2, we find that there is one definite usage of the word yom being used as an epoch, era, or longer period of time in 2:4: "This is the account of the heavens and the earth when they were created, in the day that the LORD God made earth and heaven." Here is one clear case of the word yom being used in the sense of an epoch/era within the context of Genesis 1-2 because it refers to the entire creation episode as one day! It seems unlikely that the author would suddenly change the way that he uses the word. Therefore, the rest of the occurrences in Genesis 1 seem to refer to an epoch. (In agreement with this, the Hebrew words for “morning” and “evening” [ereb and boqer] can refer to the beginning and ending of a period of time respectively).
This is completely in line with Hebrew grammar—especially considering the awkward way that the Genesis account enumerates the days. Literally, it states "and was evening and was morning day Xth." If "day Xth" were intended as the noun complement for the one evening and morning together, the linking verb should appear just once, in plural form (as the King James Version renders it: "And the evening and the morning were the Xth day"). We would expect the literal Hebrew to say, "and were evening and morning day Xth." However, as was stated above, this is not how the literal Hebrew reads. This syntactic ambiguity does not constitute a proof. However, it does at least suggest an indefinite period for each phase of the creation.
Qualification: It is often claimed that there is no place in the Bible where yom refers to an epoch/era when it is used with a numeric modifier, and so it does not refer to an epoch/era here. However, the obvious response to this argument is that of course there’s no other place where yom is used with a numerical modifier to refer to an unspecified amount of time! Indeed, there’s no other occasion in the Bible to enumerate numerous epochs of time successively.
2. The events of the 6th day
Another reason to think that the "days" of Genesis are not 24-hour periods is that the events of the 6th day seem to span a much longer period of time. Genesis 2 zooms in on the 6th day and records a detailed account of the events that occurred therein. If we hold to a 24-hour period scenario, then we have to believe that in 24 hours, God made Adam, God planted a garden, Adam cared for the garden, Adam named the animals, Adam discovered that no animals were suitable helpers, and God created Eve. This seems highly unlikely. Also, when God presents Eve to Adam in Genesis 2:23, Adam states happa'am—a phrase carrying the connotation of "at last!" This indicates that Adam had been waiting at least some time for Eve.
3. The gap theory
One interpretive option of the creation account hypothesizes that there is a gap of time between Genesis 1:1-2 and the rest of the creation episode. On this view, Genesis 1:1 describes the original creation of the universe, and Genesis 1:2 describes a great, cataclysmic judgment of the earth in which “the earth became formless and void,” possibly due to the angelic fall (see Isaiah 14 and Ezekiel 28). The account in Genesis 1:3 and following therefore is the account of the recreation of the heavens and the earth as God began to do a new work focused on man. While it is beyond the scope of this paper to argue for this position, this remains a possible way to understand the timing of the angelic fall (and thus explain Satan’s presence in chapter 3). Additionally, when the words translated "formeless and void" (tohu and bohu) are used in proximity, they seem to describe a situation resulting from judgment (cf. Isa 34:11; Jer 4:23). If this view is correct, then it is possible that a great amount of time passed during the period between Genesis 1:1-2 and the rest of the creation account.
4. God's existence is compared to the longevity of the mountains
Numerous passages including Psalm 90:2-6, Proverbs 8:22-31, Ecclesiastes 1:3-11, Micah 6:2, and Habakkuk 3:6 all indicate that the age of the universe is analogous to the age of God's Presence and plans (i.e. immeasurably ancient). This suggests that the age of the universe is so ancient that it is beyond human comprehension.
5. The analogy with God's work week.
Exodus 20:10-11 states, "…for in six days the Lord made the heavens and the earth and rested on the seventh." However, as Hebrew scholar Gleason Archer states, "By no means does this demonstrate that 24-hour intervals were involved in the first six 'days,' any more than the 8-day celebration of the Feast of Tabernacles proves that the wilderness wanderings under Moses occupied only eight days." This is similar to the Sabbath year, which also is analogous to the 7 days of creation (cf. Leviticus 25:4). Therefore, the emphasis in Exodus 20 is on the principle of one out of seven, not on the duration of the days of creation.
6. The poetic nature of Genesis 1:1-2:3
The literary genre of Genesis 1:1-2:3 has been described as prose narrative. In other words, it is a narrative sequence that has strong poetic elements. One example of a poetic element is that the days of creation appear to be organized such that days 1-3 describe locations, while days 4-6 describe the inhabitants of those locations:
1. light and dark 4. lights of day and night
2. sea and sky 5. animals of water and air
3. fertile earth 6. land animals and man
7. rest and enjoyment
As C. John Collins notes, “we may simply conclude from this high level of patterning that the order of events and even lengths of time are not part of the author’s focus; this is the basis of what is often called the literary framework scheme of interpretation. In this understanding, the six workdays are a literary device to display the creation week as a careful and artful effort.” However, while recognizing the poetic literary structure of Genesis 1:1-2:3 can be helpful in interpreting the passage, it would be a mistake to simply dismiss the truth-claims of this passage as being purely metaphorical and poetic. This passage is not simply prose—it is prose narrative. Therefore, it is wrong to dismiss the order of events and lengths of time as being altogether unimportant in interpreting this passage. Rather, what we should expect from a prose narrative is that poetic forms are used to communicate real truth. Thus we should expect to find words used in an idiomatic and poetic sense. This perfectly accords with seeing the “days” in this passage as being epochs or eras.
7. The nature of the 7th day.
Finally the 7th day in Genesis is not closed out—we are still in it. All of the other days state, "and there was evening, and there was morning, the Xth day"—thus closing out the day. However, the 7th day is never closed out. It is as though we are still in the 7th day. This is confirmed by a clear understanding of the nature of God's rest on the 7th day. As an omnipotent Being, God does not get tired or weary, and so the best way to understand His rest is that He ceased all activity of special creation. He obviously did not stop all activity for one day because everything would disintegrate without His sustaining hand upon creation. Finally, another reason to believe that we are still in the 7th day is that Hebrews 4:4-10 and Ps. 95:7-11 indicate that God is still resting in the "7th day." One day God will continue His creative activity, and he will create a new heavens and a new earth. If we are still in the 7th day, then it follows that the 7th day is an epoch; and if the 7th day is an epoch, then so are the other “days” of creation.
These are just a few biblical reasons to believe in an old earth. For more information, I would recommend the following books:
- Genesis 1-4: A Linguistic, Literary, and Theological Commentary by C. John Collins
- The Genesis Question and A Matter of Days both by Hugh Ross
- A Survey of Old Testament Introduction by Gleason Archer
- Three Views on Creation and Evolution by J.P. Moreland and John Mark Reynolds
- The Genesis Debate by David Hagopian.
- The Lost World of Genesis One by John Walton
The following is a scientific description of the possible development of days of creation that is adapted from Ross’ The Genesis Question:
- Introductory remark: Note that the vantage point from which creation is described is the surface of the earth (Gen. 1:2).
- Heavenly bodies created (Gen. 1:1) – The big bang theory states that space time and matter all came into existence from a “singularity.” This remarkably resembles Genesis 1:1 – “In the beginning (time), God created the heavens (space) and the earth (matter). The earth was initially covered with a thick layer of gas and dust not allowing light to penetrate. This is probably a standard condition of planets of the earth’s mass and temperature. The initial conditions described in the Bible are accepted by science: dark, formless, and void.
- “Let there be light” (Gen. 1:3) – Atmosphere became translucent to allow some light to reach the surface of the water, a critical prerequisite for the introduction of life (photosynthesis).
- Development of the hydrologic cycle (Gen. 1:6) – The perfect conditions of temperature, pressure and distance from the sun would allow all forms of H2O (ice, liquid, and gas) – all necessary for life.
- Formation of land and sea (Gen. 1:9-10) – Seismic and volcanic activity occur in the precise proportion to allow 30 percent of the surface to become and remain land. Scientists have determined that this is the ideal ration to promote the greatest complexity of life forms.
- Creation of vegetation (Gen. 1:11) – Light, water and large amounts of CO2 set the stage for vegetation. God miraculously creates vegetation, and this was the first form of life.
- Atmospheric transparency (Gen. 1:14) – Plants gradually produced oxygen to a level of 21%. This (and other factors) caused a transparent atmosphere to form and permitted “lights in the heavens” to become visible, thus marking day, night, and the seasons.
- Creation of small sea animals and birds (Gen. 1:20) – Scientists agree that these were the first animal life forms of all classes discussed in the Bible.
- Creation of land animals (Gen 1:24) – The final life-forms prior to Man were created: quadrupeds and rodents.
- Creation of Man (Gen 1:26) – Final creature appearing on earth.
- No additional creation (Gen. 2:2) – No unique creation has occurred since.
 Archer, Gleason L. "A Response to The Trustworthiness of Scripture in Areas Relating to Natural Science," in Hermeneutics, Inerrancy, and the Bible. Edited by Earl D. Radmacher and Robert D. Preus. (Grand Rapids, Michigan: Academic Books, 1986), pp.329.
 Collins, C. John. Genesis 1-4. (Phillipsburg, New Jersey: P&R Publishing, 2006), pp. 73.
 A thorough understanding of Genesis 1 requires considering the original Hebrew text. In verse 16, the 4th day is described and one might assume that the sun and the moon were created after the formation of plants. However, the actual Hebrew verb and tense used in conjunction with the words in Genesis 1:1 correctly indicate that the sun and moon “became visible” on the surface of the earth on day 4. (Note that the vantage point of creation is the surface of the earth [Gen. 1:2]).