Triune God is not only Being and Becoming, but also Non Being and Non Becoming ‘Unchanging’ eternally.
We can catch a glimpse of this revelation in the following verses of the Scriptures in the Old and New Testaments:
The text of Exodus 3:14: “וַיֹּ֤אמֶר אֱלֹהִים֙ אֶל־משֶׁ֔ה אֶֽהְיֶ֖ה אֲשֶׁ֣ר אֶֽהְיֶ֑ה - God said to Moses, "Ehyeh asher ehyeh (I will be what I will be)," The Amplified Bible Classic Edition translates the essence of the Hebrew as “And God said to Moses, I Am Who I Am and What I Am, and I Will Be What I Will Be.”
What is relevant to note here is that the Hebrew word אֶֽהְיֶ֑ה - Ehyeh’, is a verb ‘to be’ in the 1st person future tense, that is, “I will be”. As such, I perceive, within this proclamation of Triune God, a revelation of the Being (the ‘I’) and Becoming (the ‘will be) and the Becoming Being (I will be) Nature and Being of Triune Divinity.
The revelation given by the Almighty to John the Apostle was “I am the Alpha and the Omega, the Beginning and the End,” says the Lord, “who is and who was and who is to come, the Almighty.”
John the Apostle later used the phrase “who is and who was and who is to come”, as reference to the Almighty..
John also heard in the revelation vision, the proclamation of the four beasts to the Divine One who sits on the throne, the Lord God Almighty, as: “Holy, holy, holy, Lord God Almighty, Who was, and is and is to come.”
There are therefore two assertions recorded in Revelation of Lord God Almighty as “Who is, Who was and Who is to come” and one as ‘Who was, Who is and Who is to come.”
These assertions are consistent with the revelation given to Moses in Exodus 3:14 for the Being Becoming and Becoming Being of Triune Divine can also be expressed as the Who is, Who was and Who is to come of Triune God.
For the Being Becoming, Who is, before the Being Becoming, was, and is to be the Being Becoming, after.
Who is, is not Who was, and also not Who is to come.
For Who was, Who is has not become yet and for Who is, Who is to come has yet to become.
As such, before Who was became Who is, Who is has not become, has no being, was non being. Only in the Becoming does Who is have Being.
When Who is to come becomes Who is, Who is becomes Who was. Therefore Who was, is the non Being of Who is, even as Who is, is the non Being of Who is to come.
As such, for me, being becoming-non being-becoming being though distinct are inherently, intrinsically and inseparably one, even as, was, is and will be, though distinct, are also inseparably one, in being becoming -non being-becoming being.
Yet in all these, Triune Divinity, the I AM WHAT I AM, I WILL BE WHAT I WILL BE, is the eternally unchanging is, was and is to come Triune God
As such, what I perceive the Unchanging or Non Becoming Nature and Being of Triune God to be inseparable, intrinsically and inherently One, with and in Being Becoming-Non Being-Becoming Being of the Who and What of Triune Divinity.
For me, it is then proper to confess Triune God as not only Being and Becoming, but also Non Being and Non Becoming(Unchanging) eternally.
In the Oneness of God, the Triune present I Am, was the past I AM and will ever be the future I Am in Being Becoming-Becoming Being-Non Being-Non Becoming eternally.
But more than that, in the Word(ὁ λόγος) flesh(σὰρξ) became(ἐγένετο), the Eternal Son becoming a created human being. Now there is a created human, being becoming, becoming being, non being and non becoming, within and partaking of Triune Divinity, in the whole of Divine Being Becoming-Non Being-Becoming Being-Non Becoming, as divinely and humanly possible, eternally.
Such is the glory, pleasure and will of Triune God, for Triune Divinity and all creation, in and though the Incarnate Son, the human, the man Christ Jesus. For in him all the fullness of Deity dwells bodily.
 Chabad.org The Complete Jewish Bible.
 See pealim.com : Conjugation of לִהְיוֹת; Verb – PA'AL; Root: ה - י – ה; Meaning - to be; 1st person future tense
 Revelations 1:8
 NKJV Revelations 1:8
 Revelations 1:4
 Revelation 4:8 NKJV
 John 17:22 NKJV“And the glory which You gave Me I have given them, that they may be one just as We are one: I in them, and You in Me; that they may be made” perfect in one”(more accurately in context: made complete in oneness)
NIV Translates it as: “I in them and you in me—so that they may be brought to complete unity. Then the world will know that you sent me and have loved them even as you have loved me
 Ephesians1:4-6 “ just as He chose us in Him before the foundation of the world, that we should be holy and without blame before Him in love, 5 having predestined us to adoption as sons by Jesus Christ to Himself, according to the good pleasure of His will, 6 to the praise of the glory of His grace, by which He made us accepted in the Beloved.” NKJV
Ephesians 1:9-12 “9 having made known to us the mystery of His will, according to His good pleasure which He purposed in Himself, 10 that in the dispensation of the fullness of the times He might gather together in one all things in Christ, both which are in heaven and which are on earth—in Him. 11 In Him also we have obtained an inheritance, being predestined according to the purpose of Him who works all things according to the counsel of His will, 12 that we who first trusted in Christ should be to the praise of His glory.” NKJV
See also Revelation 4:11
 Ephesians 1:9-10 “9 having made known to us the mystery of His will, according to His good pleasure which He purposed in Himself, 10 that in the dispensation of the fullness of the times He might gather together in one all things in Christ, both which are in heaven and which are on earth—in Him” NKJV
 “For in him all the fullness of the Deity dwells bodily” World English Bible (WEB)