"I am" in John's Gospel
In John 8:58, the Gospel writer records Jesus saying, "Before Abraham was I am." Since the statement is not "Before Abraham was I was," it is easy for some moderns reading through certain metaphysical assumptions to conclude that this is a statement of the atemporality of God, or about the nature of time in general. While those ideas may or may not have a place in philosophical theology, they can hardly be demonstrated from the biblical testimony and certainly not from this verse.
This approach reads too much ontology (ultimate reality) into the verse without considering how the verse and the concept function as part of the larger Gospel. That is, this is not a propositional statement about ultimate reality or the nature of time, but part of the witness to Jesus as the Christ cast in the unique style and vocabulary of the Fourth Gospel.
There are several points to consider here. John is the only Gospel that uses the "I am" statements of Jesus as a framework for presenting his Gospel. New Testament scholars would here discuss whether these are the exact words of Jesus or John’s style of structuring the teaching of Jesus. In any case, the uniqueness of these sayings to John’s Gospel is noteworthy. That suggests these "I am" sayings are part of how John wants us to hear his testimony about Jesus. And they are clearly contrasted at the beginning of the Gospel with counter "I am not" statements from John the Baptist:
John the Baptist:
There are three basic types of sayings here relating to Jesus. One set of sayings is metaphorical (those in green) in which Jesus identifies himself in comparison to something else, usually in response to some action that he has performed. For example, "I am the bread of life" follows a feeding miracle. The implication here is that the actions of Jesus demonstrate who he is for those who are willing to believe (2:23, 7:31; however, note the message for the later church in 20:29). This is an outworking of the theme of revelatory "signs" that are also unique to John’s Gospel. The "I am" sayings are an explanation of the signs that move beyond the physical actions of Jesus.
A second type of saying is a self-identification formula (those in brown), either Jesus identifying himself in response to someone’s inquiry ("I am he"), or identifying himself in relation to God/Father ("I am in the Father"). There is one other person in John’s Gospel who uses the same formula of self-confession, the healed blind man (9:9): Some were saying, "It is he." Others were saying, "No, but it is someone like him." He kept saying, "I am the man." It is interesting that this statement becomes a testimony to Jesus as the Christ (9:37-38).
Note that in both of these types of sayings an object (technically a predicate nominative) follows the verb. The third type of saying lacks an object to the verb, leaving it as a simple statement of existence. This occurs in only one saying, 8:58.
Now, the question becomes, what does John intend, or what is the rhetorical effect, of using these "I am" sayings as a thematic element of the Gospel? If we take the Prologue of John (1:1-18) as a thematic introduction to the Gospel, then the purpose in writing the Gospel would seem to be Christological, to present Jesus as the Christ, the incarnate Son of God. One element of that for John, also revealed in the Prologue, is that for Jesus to be the Son of God, then he would also be pre-existent; that is, that as the Son of God he existed before Jesus was born. This would be a crucial element for any claim to the deity of Jesus. (The actual idea of pre-existence comes later in the church; John is actually trying to establish more the continuity of God at work in human history, although he does provide the basis for the idea of pre-existence).
This Christological intention for the Gospel becomes even clearer when we read John’s own stated purpose for writing the Gospel in 20:30-31:
Now Jesus did many other signs in the presence of his disciples, which are not written in this book. But these are written so that you may come to believe that Jesus is the Messiah, the Son of God, and that through believing you may have life in his name.
In this context, the metaphorical and self-identification "I am" sayings seem relatively clear in their intent. They are various ways to define Jesus both in terms of his actions (both words and "signs") and in relation to God the Father. This leaves the one statement in 8:58 in which Jesus simply says "I am" as somewhat enigmatic. That this saying intends to affirm the "pre-existence" of Jesus, in line with 1:1-2, seems obvious.
However, the form of the saying is interesting. We might expect this saying to be in a past tense if it were a simple statement of fact: "before Abraham was, I was." We could explain the verbal form by citing all the other "I am" sayings and assuming that this saying simply conforms to all of those. However, a closer analysis may suggest that this statement is the basis for all the others.
There is precedent in Old Testament traditions for a similar enigmatic "I am" statement. Exodus 3 recounts Moses’ encounter with God at the burning bush on Mount Horeb. When Moses asked whom he should tell the people sent him to deliver them from Egypt, God revealed himself as "I am" or "I will be" (Ex 3: 14). While that statement is in Hebrew, the grammatical form is equally enigmatic, with the only predicate for the verb "I am" being a repeated "I am."
There have been numerous debates over the precise meaning of this revealed name for God. Most scholars now understand that this is not a statement of ontology, but a revelation of the character of God that needed more than a propositional statement to be understood or believed. In that context, it is not an ontological statement of ultimate reality, which would have little meaning for the Israelites in that context, but a statement of God’s character in terms of what he was about to do for the people. In other words, who God is would become apparent in what he would be and do in human history. And of course, in that context, the definition of God unfolds in the revelatory events of the exodus itself.
It was only after the Israelites had escaped from Egypt that they gave an object to their belief (Ex 14:31). God would forever become identified in terms of that defining moment of his self-revelation in history. Israel’s confession about God would arise out of their experience of God’s historical self-revelation in the Exodus, and would give definition to God : "I am the LORD your God, who brought you out of the land of Egypt, out of the house of slavery" (Exod 20:2).
So, while the "I am" statement of Exodus 3 at first appears enigmatic, in the context of the exodus it becomes a way to affirm the self-revelatory acts of God in human history and so to affirm God as active and creative in human history. God is the only definition of God. For us, or the Israelites, the only definition of God is the self-revelation of God that we experience or that we believe because of the testimony of others. Who is God? He says, "I am." How do we know that? He says, "Watch! Because I am who I will be in your history."
This is the likely background against which John is using the self-identification formula in John 8:28. Since Hebrew has no “tense” that refers to time, the statement in Exodus 3:14 becomes a functional name for God, a name that described God in relation to his saving revelation in history. Note how this becomes more obvious in the latter part of that verse: “Thus you shall say to the Israelites, ‘I AM has sent me to you.’” It is that concept, not any dimension of time or tense, that John is using in applying the Greek equivalent of that name to Jesus. It might help to note that the form of “I am” in the Greek of John is the exact form of the Greek translation (the Septuagint) of Exodus 3:14. While affirming the preexistence of the Son of God in relation to Abraham, he is also linking Jesus to those saving revelatory acts of God in human history, specifically the exodus. In effect, John is saying that the same God who was at work revealing himself to the Israelites in the exodus, is now again at work in human history revealing himself in Jesus who is the Christ.
An interpretive paraphrase of all this might be: “Before Abraham came into being, God was already at work in human history, and it is this same God that has worked throughout human history to reveal himself as a God of salvation, deliverance, and grace who stands before you now in Jesus the Christ.” It takes all this for us. First century Jews and Christians familiar with the Old Testament would have understood all of this in the simple "Before Abraham came to be, I AM."
I would suggest that this is the primary purpose, not only of this specific saying, but of all the "I am" sayings in the Fourth Gospel, as well as John’s use of the idea of the "signs." This is also part of the significance of the healed blind man’s confession when he says (9:32-33) "Never since the world began has it been heard that anyone opened the eyes of a person born blind. If this man were not from God, he could do nothing."
So, rather than this verse implying anything metaphysical or ontological that could aid us in deciding a theory of time to determine whether God exists outside of time, I think it does almost the opposite. It affirms that the same God who has revealed himself throughout human history, and who has been known by those self-revelatory actions in history, is now revealing himself yet once again in Jesus as the Christ. This becomes the definition of Jesus in John’s Gospel, that he is the "I am" of Exodus, and if the people were willing to understand his words and actions ("signs"), they would recognize him. And of course, for John, it is not the miracles or even the teachings of Jesus that do this. Finally, it is the resurrection that is the defining revelatory event in Jesus’ life, confessed ironically by the skeptical Thomas as he declares about the risen Christ (20:28), "My Lord, and my God!"