Exodus 3:13-16
God calls Himself by two names here: The first name, "I AM WHO I AM," is mind-blowingly huge. We can't get our limited understanding around it.
The second name is "The Lord, the God of your fathers, the God of Abraham, the God of Isaac, and the God of Jacob." He refers to this as "My name forever... My memorial-name to all generations." Both are obviously His names forever, but He underscores the second one here. Why?
To me these two names stand in juxtaposition, for a reason. The reason is this:
For thus says the high and exalted One
Who lives forever, whose name is Holy,
"I dwell on a high and holy place,
And also with the contrite and lowly of spirit
In order to revive the spirit of the lowly
And to revive the heart of the contrite. ..."
Isaiah 57:15
God is unfathomable, perfect, and forever exalted. He is the I AM. He cannot be contained by anything; no one can fully understand or explain Him. If we may approach Him, it is on His terms only.
The second name, by contrast, expresses connectedness and intimacy. God has chosen to be our God, the God of His people. We still may approach Him on His terms only, but this name says, "We are bound together forever." In a sense, it is a family name. He stresses to His people that this will be His name to all generations, because all generations need to be reminded that He has called us first and foremost to relationship with Him. Not to service, not to a lifestyle, but to Himself.
The unfathomable One calls us to know Him.
"even as You, Father, are in Me and I in You,
that they also may be in Us"
(from John 17:21)