Since it has been brought up a few time, I though it cool to post this interpretation of this part of Genesis 2:
http://biologos.org/blog/genesis-creation-and-ancient-interpreters-on-the-day-you-eat-of-it/
One issue that occupied the attention of many early interpreters is found in Genesis 2:16-17, where God warns not to eat of the tree of the knowledge of good and evil, “for on the day you eat of it you shall die.”
The problem is well known: Adam (and Eve) did eat of the fruit, but they did not die on that day. In fact, Adam continues to live until the age of 930 (Genesis 5:5), and Eve, we can presume, had a long life as well.
One way of resolving this problem was to do what many Christians and Jews have done throughout history: look elsewhere in the Bible for a resolution. The principle behind this approach is that God is the author of the Bible, and so it is “mutually interpretive.” A common way of putting it among Christians, at least Protestants, is “scripture interprets scripture.”
Based on that principle, Psalm 90:4 was brought into the discussion: “a thousand years in your sight are like yesterday when it is past, or like a watch in the night.” A glance at Psalm 90 will show it is not concerned with the Adam story. The psalm is making the point that God is from everlasting to everlasting (v. 2), although people come and go quickly, in what is like a moment for God—like a single day, like a watch in the night (vv. 3-6).
Even though Psalm 90 does not address the question of Genesis 2:16-17, the connection between the two is not as random as one might think. Psalm 90:3-6 refers to death—specifically, the “sons of men” (literally, “sons of Adam”) returning to dust, or like grass they are here today and gone tomorrow (vv. 5-6). Also, as we read in the rest of the psalm, God is clearly angry with the Israelites for their “iniquities” and “secret sins” (v. 8).
You have in these three verses the use of the word “adam,” a reference to some trespass, and death described as a return to dust—and all this happening from God’s perspective in a span of time from morning to evening. Whether or not the psalmist intended to reflect the Adam story (Genesis 2:7), it is easy to understand how his choice of words would encourage interpreters to see Psalm 90 as commenting somehow on the Garden story, where you also have an “adam” retuning to dust in the face of God’s anger for his iniquities.
Given this overlap there is only one more element of Psalm 90 to apply to Genesis to make the connection complete. Maybe the divine day in Psalm 90:4 also applies to the Garden story: Adam’s life span, from God’s perspective, is also a mere day in length.
Before we got too excited thinking that Psalm 90 actually solves the dilemma of Genesis 2:16-17, we should note how the rest of the psalm plays out. In v. 10 the psalmist leaves the poetic description of death in vv. 3-6 and plainly says that the human life span is very brief, a mere 70-80 years, a mere moment compared to God. It seems clear that the point of the psalm is simply this: “Lord, you are everlasting and our time on earth is but a moment, relatively speaking. So relent of your anger and rather teach us to be mindful of how brief our stay here is.” (vv. 11-12)
Psalm 90 does not answer the question of the “day” of Adam’s death in Genesis 2, but you can see why—guided by the principle that all of Scripture is “connected” somehow—one might bring these two together.
In the New Testament, Peter picks up on this in 2 Peter 3:8 where he says, “with the Lord one day is like a thousand years, and a thousand years are like one day.” Peter is not talking about Adam’s death, but applies the language of Psalm 90 to another issue entirely. His readers were apparently concerned about the delay in the Lord’s return. Peter was simply telling them that “delay” is a relative term, and so “the Lord is not slow about his promise, as some think of slowness” (v. 9).
Other early interpreters, however, honed in on Psalm 90 to reconcile God’s warning in Genesis 2:16-17 with the fact that Adam died at the ripe old age of 930. After all, if a day in God’s mind is like 1000 years, and Adam died at 930 years of age, Adam died in a divine day—with 70 years to spare. And so we read in Jubilees 4:29-30 (written in the middle of the 2nd century B.C.):
Adam died, and all his sons buried him in the land of his creation, and he was the first to be buried on earth. And he lacked seventy years of one thousand years; for one thousand years are as one day in the testimony of the heavens [i.e., Psalm 90], and therefore it is written concerning the tree of knowledge: “On the day you eat of it you shall die.”
Another way of looking at the problem of Genesis 2:16-17 is simply to say that on the day Adam ate of the fruit, he was barred from eating of the other tree, the tree of life (Genesis 2:22-24). Adam had only been barred from the tree of knowledge, and so we can presume he had free access to the tree of life. But once barred from the tree of life, mortality was introduced. Hence, “on the day you eat of it you shall die” would mean that immortality was removed, and Adam and Eve then entered a state of mortality.
There are other solutions that have been proposed in the history of interpretation. But, once again, the more basic point should not be lost. In the pivotal opening chapters of the Bible, we have an ambiguity that readers worked to resolve.