The firstborn son is chosen and is not related to birth order. 1 Chronicles26:10 has another example. Shimri was chosen to be firstborn by his father but he was not born first. I think the Bible's point is one the sons' of God was chosen to be God the Son. God knew that Jesus would be the obedient son. The Creeds say the Triune God was and is God forever. It's easier to see the Son s subservient to the Father when we see the Son as chosen and anointed before Creation.
Your partly right enoch regarding the "firstborn" issue because the title "firstborn" does not necessarily refewr to the one born first or even born at all. The father can designate whomever he chooses "firstborn." Exodus 4:22, And thou shal say unto Pharaoh, Thus saith the Lord, Israel is my son, even my firstborn." Also David was chosen as firstborn, by God, although he was not the eldest of his brothers.
What I do disagree with is when you said the following: " I think the Bible's point is one the sons' of God was chosen to be God the Son. God knew that Jesus would be the obedient son." Jesus Christ who is the God the Son was not chosen by God His Father. Since Jesus Christ is God He always existed as God and then at the appropriate time God sent His Son to be the Savior of the world.
Please read Philippians 2:3-10 for starters and then I'll give you more proof that Jesus was "NOT" chosen by God His Father as you say. Btw, regarding the creeds, there is nothing wrong with the creeds and they serve a valuable service. they served for the purposes of correcting various heresies that would arise. The Nicene Creed addressed the Arian heresy for example.
Creeds are also essention Christian truth. The Athanasian Creed affirms the truth of the Trinity, Christ's incarnation, resurrection, ascension, second coming, and final judgment. I could give other reasons regarding the purpose of the creeds but I hope you get the idea.
And for your information there are "Creeds" within the Bible itself. 1 Corinthians 15:3,4 is a creed. So is 1 Timothy 2:5-6. Some of them sort of summarize Christian beliefs. Any other questions I will be happy to address.
PS: Again, please read Philippians 2:3-10 and tell me how you understand what the verses are teaching.
IN GOD THE SON,
bluto