How profound and revelatory is it that when asked his name, God forever connected his identity with his existence: “I AM WHO I AM” (Exodus 3:14).
The Hebrew word Yahweh is interesting because it not only points to present existence (I AM), but the word is undefined. This means that it may also be translated “I was who I was” and “I will be who I will be.”
So not only do we have God revealing himself as one whose identity is tied with his existence, but this existence always was and always will be. God is eternal.
For one who wants to know if God exists, and if he does then who he is and what he is like, they may only need to look to God’s self disclosure of himself: “I am that I am.”
To look to the New Testament is just as profound. The Lord Jesus Christ, God in the flesh, is called the Word (John 1:1). The Savior of the world is revealed as one who has always existed in speech, and has been the Person through which everything has been spoken into existence. So not only is God in existence from eternity, but he has been speaking for all eternity. He has always been communicating, and always will be in communication with his creation.
Finally, the name Holy Spirit, the third person in the Trinity, utilizes the word “spirit,” which also means “breath.” God the Father is the essence of existence. God the Son is that essence speaking things into existence. And God the Holy Spirit is the essence that breathes life into all things.