That is easy...they never were “coexistent, coequal, and coeternal”.....who told you that they were?
I will use a number of translations so that you won’t think I am just using ‘my own Bible’...OK?
“God the Father” is spoken about freely throughout the Bible, but there is not one mention of “God the Son” or “God the Holy Spirit”......the Catholic Church invented those terms to promote its trinity.
Jesus is the created “Son of God”. He was God’s “only begotten Son” long before he came to earth as Jesus “the Christ”. One who is “begotten”, needs a ‘begetter’...one who existed first and who caused that one to exist. It is logically what makes God a “Father”.
Revelation 3:14 calls Jesus “the beginning of God’s creation”. (ESV)
Colossians 1:15-17 says of Jesus.....
“He is the image of the invisible God, the firstborn of all creation. For by him all things were created, in heaven and on earth, visible and invisible, whether thrones or dominions or rulers or authorities—all things were created through him and for him. And he is before all things, and in him all things hold together.” (ESV)
Proverbs 8 speaks of God’s firstborn.....
“The Lord brought me forth as the first of his works, before his deeds of old; I was formed long ages ago, at the very beginning, when the world came to be. Then I was constantly at his side. I was filled with delight day after day, rejoicing always in his presence, rejoicing in his whole world and delighting in mankind.” (Proverbs 8:22-23,30-31 NIV)
So, Jesus was “the beginning of God’s creation”....
He is “the image of...God”.....an image is a reflection of what it is mirroring or representing.
He is “the firstborn of all creation” meaning that he is the very first creation of his Father, and “only begotten” (monogenes) means that he is literally an “only child”.
Since all creation came “through” the Son, but not “from” him, the Son is the agency through whom all things came into existence in heaven and on earth. Jesus was working alongside his Father in the whole project. He is the “us” and “our” in Genesis 1:26.
That makes Jesus sonship unique as the only direct creation of his God and Father.
The Father is the only being to have the designation “Eternal” which literally means “no beginning or end” and since Jesus is a creation of his Father he had a beginning so he is not co-eternal.
The Holy Spirit in scripture is sometimes personified, but then so are a lot of other things in the Bible. It does not mean that God’s spirit is a person because it’s application throughout man’s history shows that it isn’t.
God’s spirit was shown to be moving to and fro over the surface of the waters when God first began his project here on earth. But nowhere does the Bible call the Holy Spirit, “God”. Jesus is never called “God” either. He is called “theos” which can be applied to any one who is a god, of divine origin, or who has been granted divine authority.
The Holy Spirit is never called “theos” but as long as God has existed he has always been a powerful Being. His spirit is the administration of his immense power. It is not and never has been a person.
In ancient times when Moses first led the Israelites out of Egypt, he found the going too difficult as this was a vast multitude of difficult and rebellious people that he was trying to lead through the harshest of environments.
Numbers 11:16-17 tells us what God said to Moses....
“The Lord said to Moses, “Gather to me seventy men of the elders of Israel, whom you know are elders of the people and officials over them, and bring them to the tent of meeting; let them take their position there with you. Then I will come down and speak with you there, and I will take part of the Spirit that is on you, and will put it on them, and they will bear some of the burden of the people with you, so that you do not bear it all by yourself. (NET)
Is this describing a “person”....or is this describing the dissemination of God’s power among many?
When the disciples received the Holy Spirit at Pentecost, there were 120 of them gathered in a room. The Holy Spirit was distributed among all of them. Is this a person, or again, the dissemination of God’s power among many who could then do supernatural things?
In all scripture that has Jesus at God’s right hand, there is not a single mention of the Holy Spirit being at his left. In fact in almost every scripture, God and his Son are spoken about but the Holy Spirit is invariably missing. (John 10:30; John 17:3)
A study of the Bible itself rather than church doctrines clarifies many things and exposes false doctrines that crept in long ago and have become Bible truth to many....when they never were.
We should allow the whole Bible to speak...it has much to teach us.