TWO ELEMENTS IN Exodus 3 demand attention.
The first is the dramatic introduction of "the angel of the LORD" (3:2). Initially, at least, Moses does not perceive an "angel." The text reads, "There the angel of the LORD appeared to him in flames of fire from within a bush" – but this cannot mean that an angelic being appeared within the flames, differentiable from the flames, for what draws Moses' attention is the bush itself which, though apparently burning, was never consumed. The manifestation of "the angel of the LORD," then, was apparently in the miraculous flames themselves. Strikingly, when the voice speaks to Moses out of the burning bush, it is not the voice of the angel but the voice of God: "God called to him from within the bush, 'Moses! Moses!'" (3:4). The ensuing discussion is between God and Moses; there is no further mention of "the angel of the LORD."
On the face of it, then, this "angel of the LORD" is some manifestation of God himself. We shall have occasion to think through other Old Testament passages where the angel of the Lord appears – sometimes in human form, sometimes not even explicitly called an "angel" (recall the "man" who wrestles with Jacob in Gen. 32), always hauntingly "other," and always identified in some way with God himself.
We might well ask if, when the text before us records that "God said," it really means no more than that God spoke through this angelic messenger: after all, if the messenger speaks the words of God, then in a sense it is God himself who is speaking. But the biblical manifestations of "the angel of the LORD" do not easily fit into so neat and simplistic an explanation. It is almost as if the biblical writers want to stipulate that God himself appeared, while distancing this transcendent God from any mere appearance. The angel of the Lord remains an enigmatic figure who is identified with God, yet separable from him – an early announcement, as it were, of the eternal Word who became flesh, simultaneously God's own fellow and God's own self (John 1:1, 14).
The second element is even more important, though I can assign it only the briefest comment here. The name of God (3:13-14) may be rendered "I AM WHO I AM," as it is in the NIV, or "I will be what I will be." In Hebrew, the abbreviated form "I am" is related in some fashion to YHWH, often spelled out as Yahweh (and commonly rendered "LORD," in capital letters; the same Hebrew letters stand behind English Jehovah). The least that this name suggests is that God is self-existent, eternal, completely independent, and utterly sovereign: God is what he is, dependent on no one and nothing.
Exodus 3; Luke 6; Job 20; 1 Corinthians 7