Okay lets jave a look at LBG's supposed proof text that Jesus is a different god to the Father (basically 2 gods).
20 But Christ has indeed been raised from the dead, the firstfruits of those who have fallen asleep. 21 For since death came through a man, the resurrection of the dead comes also through a man. 22 For as in Adam all die, so in Christ all will be made alive. 23 But each in turn: Christ, the firstfruits; then, when he comes, those who belong to him. 24 Then the end will come, when he hands over the kingdom to God the Father after he has destroyed all dominion, authority and power. 25 For he must reign until he has put all his enemies under his feet. 26 The last enemy to be destroyed is death. 27 For he “has put everything under his feet.” Now when it says that “everything” has been put under him, it is clear that this does not include God himself, who put everything under Christ. 28 When he has done this, then the Son himself will be made subject to him who put everything under him, so that God may be all in all. 1 Cor 15:20-28
LBG starts at v24, bu the the passage really should start at v20. m The whole of chapter 15 is to do with the ressurection of the dead, some in Corinth were denying the ressurection of believers (v12).
Here Paul is talking about Christ handing over the kingdom to the Father at the end of the age, after all enemies have been defeated. Christ is the first fruit meaning we as the crop that follows will be resurected like Him for all eternity.
Here Paul is stressing Christs role as Mediator between God and man, Christ the God-man. Why is it so important that Jesus being God became flesh (God-man), it is of the utmost importance, it also shows why Christ is subject to the Father. Christ is not unequal or inferior. If we look at the VERB 'subject' it does not mean unequality in person it refers to 'function', the verb 'subject is in the future tense.
Subject does not imply inferiority but a difference in roles, subjection does not necessarily imply inferiority.
To put it another way, In order for God to atone for mans sins someone had to ''Subject' Himself to death (are you starting to get the picture LBG).
but Christ WILL become sjubject to Glod when all dominion, authority and power has been defeated, so the above cannot be used to explain Christ's subjection to the Father
Yet only one with unlimited ability to atone for sin could do that. He had to have unlimited ability to atone because He would be shedding His blooad for humankind. He also had to be perfect because God would not accept blemish like all human kind in the first Adam, the sacrifice had to be unblemished. Who would do that? Only God can do that! And God the Son shed His own blood for us (acts 20:28).
Now so that you can understand this a bit better, lets have a look at Romans, obedience is very key here to understanding the role of Christ as God - man, mediator and High Priest.
18 Consequently, just as one trespass resulted in condemnation for all people, so also one righteous act resulted in justification and life for all people. 19 For just as through the disobedience of the one man the many were made sinners, so also through the obedience of the one man the many will be made righteous.
Now Christ in His function subjected Himself to the will of the Father through obedience to death as the last Adam (man).
As the perfect Man Christ had to be obedient to the Father... because if He was our substitute and DISOBEYED the Father then he would not have been perfect!!!!!
Again, As the perfect MAN, Christ had to be obedient to God to fulfill God's plan to redemm humanity. Jesus voluntarily submitted to that plan, to God the Father, in order to save humanity from eternal seperation from God.
But Paul says that Christ WILL become subject to the Father in the future when all dominion, authority and power has been defeated, you are relating his subjection to obediance to death on the cross
In reference to the Kingdom, this is the Kingdom innaugurated by Christ and will be consumated at His return, His function as Mediator and High Priest is what is being taked about, He is still co equally God, yet subordinate in refernce to His obedience unto death to save men as the last adam.
So why WILL Christ become subject to God when all has been defeated, you are not addressing the main points in the question
As a Side note, refering to the Kingdom and how that plays out depends on your eschatology.
You see as I said earlier, it is because you have the wrong idea of who God and Jesus are brings you to all the wrong conclusions about who God says He is.
Blessings
Phil