Summary: Even though we find the name Yahweh in the Bible many times before Moses’ encounter with God at the burning bush, it is the first time that the name is explained to us.The name Yahweh is used more than any other name for God in the Old Testament. It occur
Purpose: To describe the comprehensive nature of the name Yahweh.
Aim: I want the listener to gain a deeper affection and reverence for God.
INTRODUCTION: The first name for God in the Bible (Genesis 1:1) is the Hebrew name "Elohim" which reveals God as "The Mighty or Strong One" and often highlights God as Creator.
The second name for God that we find in Scripture is Yahweh or Jehovah. The name Yahweh is used more than any other name for God in the Old Testament. It occurs 6,823 times. The burning bush was not the first time that the name YAHWEH was revealed. The first mention of Yahweh is in Genesis 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. (NAS)
Even though we find the name Yahweh in the Bible many times before Moses’ encounter with God at the burning bush, it is the first time that the name is explained to us.
Vs.13-15 I. Who is Yahweh? "I AM WHO I AM"
I AM WHO I AM literally means, "I will be what I will be." This name is from the Hebrew verb, "to be." This became the most sacred name for God that has been revealed to us. That name was so sacred to the Jews that they refused to pronounce it. This is probably because of what God said in the Ten Commandments: Exodus 20:7 "You shall not take the name of the LORD your God in vain, for the LORD will not leave him unpunished who takes His name in vain. (NAS)
Since the original Hebrew language had no vowels the actual pronunciation has been lost. Hebrew scholars pretty much agree that Yahweh is more likely to be the correct way to say the word.
In verse 13 Moses asks, "...If ... the people of Israel ... ask me, ’What (mah) is his name?’ what shall I say to them?’ (Ex. 3:13). The normal way to ask a name is to use the pronoun mî; to use mah invites an answer which goes further, and gives the meaning (’what?’) or substance of the name.
"This helps to explain the reply, namely, ’I AM WHO I AM’ (’ehyeh ’ašer ’ehyeh). And he said, ’Say this to the people of Israel, ’I AM has sent me to you’ ’ (Ex. 3:14). By this Moses would not think that God was announcing a new name, nor is it called a ’name’; it is just the inner meaning of the name Moses knew." 
We know this is true because, God spoke further to Moses and said to him, "I am the LORD; and I appeared to Abraham, Isaac, and Jacob, as God Almighty, but by My name, LORD, I did not make Myself known to them. (Exodus 6:2--3 NAS)
From this intriguing phrase, "I AM WHO I AM" we can learn at least six important things about God.
A. Yahweh is self-sufficient
The fact that "GOD IS" implies that God does not need anything or anyone else. We depend on many things outside of ourselves in order to exist. We cannot live without food, water, air and many other things.
God is the Creator, but He was never created so He doesn’t need anything outside of Himself. Isaiah 44:24 Thus says the LORD, your Redeemer, and the one who formed you from the womb, "I, the LORD, am the maker of all things, Stretching out the heavens by Myself and spreading out the earth all alone, (NAS)
When Paul was preaching on Mars Hill he said, Acts 17:24--25 "The God who made the world and all things in it, since He is Lord of heaven and earth, does not dwell in temples made with hands; nor is He served by human hands, as though He needed anything, since He Himself gives to all people life and breath and all things; (NAS)
B. Yahweh is a person
I AM is a first person pronoun so God is not just a force or an idea. 1 Thessalonians 1:9 ... you turned to God from idols to serve a living and true God, (NAS)
C. Yahweh is eternally alive
Exodus 3:15 God, furthermore, said to Moses, "...This is My name forever, and this is My memorial-name to all generations. (NAS)
God had no beginning and will have no end. This also implies that God lives in the eternal present: He is! God didn’t say "I was" or "I will be."
Isaiah 43:10 "...So that you may know and believe Me and understand that I am He. Before Me there was no God formed, And there will be none after Me. (NAS)
Isaiah 48:12 "... I am He, I am the first, I am also the last. (NAS)