Leon Morris tells us the saying is emphatic of deity.  Within the context of John's Gospel, this saying ought to be heard in concert with the seven great I-AM sayings that mark his account of the life and death and resurrection of Jesus Christ. I AM the bread of life (6:35, 48). I AM the light of the world (8:58). I AM the door (10:7, 9). I AM the good shepherd (10: 11, 14). I AM the resurrection and the life (11:25). I AM the way, the truth, and the life (14:6). I AM the true vine (15:1, 5). When we are asked to answer the question 'Who do you say that I-AM?' we need to be able to refer to all of these sayings. Beside these, we must understand that this is the Word become flesh of the prologue to the Gospel and refers us to the preexistence of Jesus Christ, that is before the Creation was created in some sense there existed the person of Christ. Before time, in God's own eternity, with God lived His Christ. Karl Barth writes, " If we understand eternity as pre-time - and we must understand in this way too - we have to recognize that eternity itself bears the name Jesus Christ."  He links the saying to Ephesians 1:4f, where we read that believers in Christ were chosen before the foundation of the created world. Sayings like this were known as hard sayings, sayings not easily understood, but absolutely necessary for understanding the way God had chosen to face His People in His Covenant with them.  The great I-AM of the Lord God who is who He is with or without His Creation is a part of what we are asked to hear when we read Jesus assertion about himself in confrontation with the Jews of his time.
The immediate context of the assertion is the saying of Jesus as the 'Light of the World'. Even a careless reading of this context cannot escape the contention in it about the Father. The conflict between Christ and the Jews has grown to such proportions in this context that Jesus is accused of being something of a bastard among them. The Jews insist that they know the Father and Jesus does not. Jesus claims against them that he does know the Father and that they do not. It is a conflict in ultimates. One is telling the truth. The other is a liar, about themselves and God. Jesus accuses his accusers of being of the devil. They accuse him of the blasphemy of a demon, deserving of death. Jesus denies that he is demon and tells them that even their father Abraham rejoiced to see the day of the glorification of him by the Father. It is obvious that the contention in the passage has to do with who the Father is in relationship to Christ and the Jews. It is as the 'Light of the World' that we are to see Jesus Christ for who he truly is as the Son of God the Father. How could he expect them to see him for who he truly is?
The saying 'I AM the Light of the World.' could be understood in a diversity of manners. Light in the ancient world was much revered, even worshipped. Greek thought struggled incessantly with its significance. Whole pantheons of gods dwelt about the secrets of the divine light of that 'logos' which was inherent in the eternal nature of the cosmos. This is the place where mankind on the earth could find its true being. The eternity of the world and the temporal nature of our kind at the center of the cosmos was an enigma to be resolved by learning to cavort with the heavenly and changeless forms, by leaving the morass of the temporal and saving all appearances in the eternity of a creator's heavens. It was a view of the world that meant a dead-end for true science, but its effect on the popular imagination of the human race was and is profoundly with us.  It provides us with a moment of deep reconsideration about the nature of reality and the development of human thought to reflect upon the fact that the Sixth Century Alexandrian Grammarian, John Philoponus, was condemned for his theory of light while Aristotle's was accepted and thrived even while Copernicus and Galileo struggled to change minds grounded in Greek traditions married to the doctrines of the Church of Jesus Christ.  How may we hear what he meant with this designation?
Besides referring to the 'I am who I am' saying of the Exodus Tradition in the history of Israel, Beasely-Murray points us to the Prophetic Tradition of the People of God. He says that the 'I am he' of the messianic hope are bound up with this light of the Lord. He understands that the so-called Second-Isaiah speaks of this One, as the obedient servant who will achieve with his life what disobedient Israel would not (Is 43:11-13). I would like to deepen our grasp of this One. In Isaiah 42:5-9, this same One is announced as the fulfillment of the covenant between Yahweh and Israel as well as God's Light to the nations (Is 42:6):
- I, Yahweh, have called you in righteousness.
I will take hold of your hand.
I will keep you and make you
To be a covenant for the people
And a light to the gentiles.
This light defines the boundaries in which the messianic hope is developed among the prophets of Israel. To understand this, we need only study its development throughout the entire vision of Isaiah. Isaiah 2:5 asks Israel to come and walk in the light of Yahweh. This forms the basis for the development of the covenant relation articulated by the Word of the Vision. Isaiah 9:2 develops the significance of the exhortation. Upon a people walking in great darkness shall dawn this light. He will be the Royal House of David in the Day of Yahweh---Wonderful Counselor, Mighty God, Everlasting Father, Prince of Peace (Is 9:6b). This David will judge and be the salvation of all that will experience the New Creation. Isaiah 42:6 is confirmed in by the work of this One:
- It is too small a thing for you to be my servant,
To restore the tribes of Jacob
And bring back those of Israel I have kept.
I will also make you a light for the Gentiles,
That you may bring my salvation to the ends of the earth.
Again, in Isaiah 60:1-3 and 19-20 we read that this light has come for the New Creation of this obedient servant of the Lord God. This light is clearly understood as God Himself; the 'I am He' of the prophets, and the great I-AM of the covenant in the history of Israel between God and the People of God. When the prophetic vision sees the Father (Is 63:16-19) of Israel and the New Creation, he is seen in this light. The fulfillment of the ancient promises rest upon the faithfulness of this One to His covenant with His People. 
We may understand that the 'Light of the World' which Jesus calls Himself in the Gospel of John is none other than the House of David for the New Creation according to the ancient prophets of Israel. It is as this David that Christ confronts the Jews of his time. In this way, we may understand that in His Person we have kept the promise the Lord God had made to this House when King David was given to reign over the Monarchy of the People of God (2 Samuel 7:12-16 cf. 1 Chronicles 17:11-14, where the sin of David, important to the Books of Samuel, has been ignored by the Chronicler). David, the obedient servant of the Lord God, Jesus Christ, is the One through whom the Father is known. It is in the light of his being that he is in the history of Israel that the People of God are to understand their Father. Here is the One who will keep the ancient promise in covenant with Israel.
When we understand this light as the background for the saying in John 8:12, then we may see what is at stake in Jesus assertion that He is the great I-AM of the prophecy. With this David is the grace and truth of the Lord God made known to His People and through His People to the entire world of nations. It is the promise of the truth of this grace with us that create the ground upon which we may stand to see our Father. Upon this ground, we may hear him for who he truly is with us. We may listen to the great I-AM of the Lord God speaking to us here. In this One, we may see the Father who is before all things created.
I believe that in this light we may understand properly the many references to God as light throughout the New Testament. In 2 Corinthians 4:4-6 we read:
- The god of this age has blinded the minds of unbelievers, so that they cannot see the light of the gospel of the glory of Christ, who is the image of God. For we do not preach ourselves, but Jesus Christ as Lord, and ourselves as your servants for Jesus' sake. For God, who said 'Let light shine out of darkness.' made his light shine in our hearts to give us the light of the knowledge of the glory of God in the face of Christ.
Again, in Colossians 1:10-14 we read:
- And we pray this in order that you may live a life worthy of the Lord and may please Him in every way; bearing fruit in every good work, growing in the knowledge of God, being strengthened with all power according to His glorious might so that you may have great endurance and patience, and joyfully giving thanks to the Father, who has qualified you to share in the inheritance of the saints in light. For He has rescued us from the power of darkness and established us in the kingdom of His Son He loves, in whom we have redemption, the forgiveness of sins.
In Ephesians 5:8-14 we read:
- For you were once in darkness, but now you are light in the Lord. Live as children of light (for the fruit of the light consists in all goodness, righteousness, and truth) and have nothing to do with the fruitless deeds of darkness, but rather expose them. For it is shameful to mention what the disobedient secretly do. but everything exposed by the light becomes visible, for it is light that makes everything visible. This is why it is said: 'Wake up, O sleeper, Rise from the dead And Christ will shine on you'.
Early church fathers heard the resonance of this light with the Great I-AM of Moses' Torah quite well. They read the Gospels in its light. Athanasius wrote in his de Decretis (22), 'When he says, I am that I am and I am the Lord God, or when Scripture says God, we understand nothing else by it but the intimation of His incomprehensible essence itself, and that He Is, who is spoken of. Therefore let no one be startled on hearing that the Son of God is from the essence of the Father, but rather let him accept the explanation of the fathers, who in more explicit but equivalent language have for from God written of the essence. For they considered it the same thing to say that the Word was of God and of the essence of God, since the word God, as I have said already, signifies nothing but the essence of Him Who Is." This champion of the Nicene Creed here passes on here the steady belief in the early church that the great I-AM of the Torah is the same as the great I-AM of the New Testament, and that this I-AM, who is the One who is who He truly is in His substantial uncreated life, has kept His ancient covenant promise to His People in the Lord Jesus Christ.  This was the burden of the invention of the term homoousion at Nicea in 325 AD. One cannot understand the revelation without being able to say that the Son was one being with His Father. There is no Son except the Son of the Father and there is no Father except the Father of the Son as the One God. This could only be understood by the Spirit of God and the Trinitarian faith was established as orthodox once and for all because of this understanding of the Bible.
Athanasius goes on in the de Decretis to find an analogy for this relationship in the relationship between the radiance of the light from the sun and the sun. Radiance was not the same as the sun, but hardly may we divorce the one from the other, because the radiance was 'of the essence' of the Sun. The Son may be of one essence with us, but he is also of one essence with His Father, and the two must be thought of as One in the orthodox understanding of the person of Jesus Christ. It was with kind of argument by which the fathers at Nicea sought to struggle against both Arian and Gnostic attempts to interpret the 'Word become flesh' and the Great 'I-AM' of God in Christ in some other light that the light provided them in the relationship between the eternal and incarnate Son and His Father, Almighty maker of the heavens and the earth.
Because of the resonance of this Word with us, Karl Barth rightly understood the church's doctrine of election in the person of the Lord Jesus Christ. He writes with this understanding: 'We cannot help them, then, simply by placing a stronger emphasis upon the biblical doctrine of God's repenting and providing a new and better translation of Ex. 3:14. Their failure was due rather to their non-adherence to the rule that the will of God as such, and therefore predestination, must be sought and found only in the work of God, i.e., in the core and purpose of that work, the name and the person of Jesus Christ.'  Outside of this Great I-AM, the human race remains captive in the darkness that lies outside of the Light that He is for us.
Tom Torrance regards this relational coherence and oneness of the Father and the Son in the Spirit of God as fundamental to knowing God for who He truly is. He writes in The Trinitarian Faith, 'Thus, they (the Nicene fathers) rejected any idea that the Son is from a being other than God, or that he is Son of God only through partaking of God, and stated quite definitely and unambiguously that the Son is of the very being of God and is God in precisely the same sense in which the Father is God, for he is uniquely and completely one with him. He is in union with the Father, the eternal 'I Am' of the Godhead."  The Light of the Great I-AM shines throughout the Creation and all its creatures in the Name of the Father and the Son and the Holy Spirit. Professor Torrance has reinforced this point in The Christian Doctrine of God, One Being, Three Persons, where he links up the concerns of the prophet Hosea with the Incarnation and the Trinity of God.  His Spirit makes the Fatherhood of God known in Christ as the great I-AM of the Godhead. Thus, revelation and reconciliation are essential in the covenant relationship that bears God's purposes to His People, and in this relationship belief and godliness are shaped by the grace and truth of the Light that brings real and saving knowledge of the God in the mystery His Being in our time. Eternity and time meet here in this place. The boundaries of this place mean that all elsewhere is rendered nowhere in its New Creation. But in this light shall live forever the children of light with their God, who is the true light shining in the world.
I believe that it is this light about which Brevard Childs would speak in his recent efforts to take Biblical Theology beyond the impasses it has met with its embrace of historical-critical methodologies assumed at this time.  This great scholar has embraced the significance of the fact that we may not divorce from Himself who God is in His Acts with Israel and the Church (pp. 354-358) and therefore we are not permitted to continue to work in the chasm posited beginning with the assumptions of J.P. Gabler in the 19th Century. Although he acknowledges the need to relate Biblical Interpretation then to modern scientific developments, he does not think that Torrance's work leads us to the fresh new approach for which he seeks (p. 406).
I have found, in fact, the opposite to be the case. Torrance's work does send me back to reading the Bible with an assumption (belief) that seeks to understand the Living God in the witness He has created through His covenant relationship with Israel and the Church, It is within the boundaries of this witness that we may learn to listen to Him, we who are on earth and He who lives beyond the space-time of the Creation. Torrance's insistence that we must learn to hear the Light of this Lord within the domain of this God's Creation makes even more intelligible our historical commentary on the Bible. In any case, I believe that we will need to follow the concerns of both of these scholars if we going to make the kind of progress we need to make in Biblical and Dogmatic Theology. Only with such progress will we become capable of taking seriously both the transcendent dimensions of the Living God with us and His personal and communal work on our behalf in the history of the world. Obviously, we will need to go beyond them, but we will not get there without going through them. This surely calls us to let go of our out-dated assumptions about the subject-object-subject relations inherent any reading of the Bible and its witness to our God.
Perhaps it will be helpful at this point to look for a moment at the relationship between the created light of the universe and the uncreated light of the Word of God. The light of the universe has provided us with a profound paradigmatic shift at the foundations of our knowledge of the nature of the world. Einstein's assumption about the constancy of the speed of light enabled him to grasp the reality of a dynamic invariance inherent in the orders of the world. If light's speed were infinite, we would still believe that Newton's 'System of the World' was sufficient to entail all the mechanics of the universe. But since the speed is constant and finite, we were compelled to learn on a fresh basis the objectivity of our experience of the universe of light. Our experience of the light is to be relativized so that we may understand it in objective relations within the radiant field of its dynamic invariance. This paradigmatic shift in our concept of universal reality is every bit as profound as the shift created when the transformation of the Ptolemaic Cosmology was forced upon our development with the struggles of Philoponus, Copernicus, Kepler, and Galileo. Biblical interpretation based upon worldviews that ultimately need to correspond with a physical reality whose nature is deeply bound up with the power of God's Word can be at any particular time in great need of reformation. It is perhaps this need that marks our time more than any other. Torrance has championed this need with us. Childs, I think, wants Biblical Interpretation to progress in the light of this need. I believe that, if we will not regard it as urgent in our time, we will continue to make our efforts archaic even while they appear the most fashionable and relevant. My hope is that we will take seriously as categories for the development of our thought the way in which the created light of the universe and the Light of the World are bound up freely in the freedom of the Lord God to be who He truly is with His Creation and His People.
In 1 John 1:5, with John 1:1-5 definitely in mind, we are told that 'God is light and in him there is no darkness at all.' He is a light the believer handles. It is intelligible and sensible to us. It is a light whose source is the relationship of the Father with His Son and the Son with His Father in the Spirit of God. It is a light whose Word has become flesh will not be denied His Rightness in His world. It is in this light that we may hear the bell toll that sounds His Word for the world to hear. It is this Word that calls us to Himself. Here is the Lord God who is the 'Light of the World'. Here we may go to the One who keeps faith with and for us in the world. Here is the One who will be not denied in His covenant with His People in His Creation. Here we are given to participate with the life and love of the light God is both in Himself and in His World. The great I-AM who is who He truly is even before Abraham and the Creation has come to face us in this way with Himself, and we do well to allow ourselves to listen to this One. Here is the source of all true Biblical and Dogmatic Theology. Here is the place where Theological and Natural Science meet. It is to this place that we must go if are going to learn to do right in the eyes of our Lord and God.
In the Apocalypse, the Book of Revelation, the final document of the New Testament of the Church of Jesus Christ, we read of the One who is the Alpha and the Omega, the One who is and who was and who is to come, the Almighty (1:8). This is the great I-AM that God is in His own eternity with His Lamb, the Living God. The final chapters of the Apocalypse tells us that the City of God does not need the sun or the moon to shine on it, because the glory of God shine upon it, which glory is the Lamb who is the King of the kings of the earth (21:23-26). This is the basis of the New Creation that shall be established fully at the coming of this One. It is this Jesus who is the David of Israel's prophecy and the bright Morning Star of the fulfillment of the covenant promise of the Lord God with us (22:16). Surely we do well to take seriously this Light of the Great I-AM of this Living God for us, especially in our interpretation of His witness in the midst of the darkness of a world that would oppose Him.
 Leon Morris, The Gospel According To John, (Eerdmans, 1971), p. 365, 473-4.
 Karl Barth, Church Dogmatics, II. 1, p. 622.
 See my essay on 'The Great I-AM of God in Biblical Covenant Relationship with His People in the Old Testament World', Quodlibet Journal, Vol. 1, Num. 8, December, 1999, www.quodlibet.net. This essay argues for a recovery of a real biblical ontology in our interpretive powers.
 See S.L. Jaki, The Road of Science and the Ways to God, (University of Chicago Press, 1978) for an account of the 'blind alleys' and T.F. Torrance, Christian Theology & Scientific Culture, (Christian Journals Limited, Belfast, Dublin, Ottawa, 1980), especially the chapter entitled 'Theology of Light' for a glimpse into this problem.
 See The Setting in Life of 'The Arbiter' by John Philoponus, (Wipf & Stock; Oregon, 1998) for an exploration of the case against this great thinker and the argument for the removal of the Anathema from his works.
 It is more than interesting to notice here that the MT Isaiah 53:11 does not contain a reference to this light. But the Septuagint does, and this reading is reflected in the Isaiah manuscripts become known as the Dead Sea Scrolls. Evidently, the resonance of this light with John 8:12 was too bright for some to bear at one time.
 I have discussed the problem of the 'essence' of God in His Acts in history with the 'essence' of God in Himself outside of the history of the world in my Quodlibet Journal article. My argument sides with the early fathers on this point against the modern tendency to believe we can only know God in His Acts with us and not who He is in Himself. Thought we must surely be able to differentiate His Being in this way, still we must be able to identify the two as the One God in some real way.
 Church Dogmatics, II.2, p. 191. On pages 188-194, Barth argues that the freedom of God's 'essence' does not allow us to conceive in some static manner the living of this being with us. He would translate 'I am who I am' by 'I will be who I will be', in order to assert that the Word Himself must be free to relate Himself to Man and God as only He is free to do, in the freedom of the Word become flesh for us.
 T.F. Torrance, The Trinitarian Faith, (T & T Clark, 1988), p. 122. In his chapter on God of God and Light of Light, Professor Torrance explores with great insight the use of 'light' as the means to grasp the significance of the relational veracity that must shine in the revelation of God's Word with us. The Trinity of God, Father, Son, and Holy Spirit is the light in which we may see God, the world, and ourselves. It is in this light that John Philoponus sought to overcome the dead-ends in Aristotelian thought and develop a physics of light that has only in our time begun to come to light (p. 108).
 T.F. Torrance, The Christian Doctrine of God, One Being, Three Persons (T & T Clark, 1996), pp. 118-127.
 B.S. Childs, Biblical Theology of the Old and New Testaments, (Fortress Press, 1992).