OK Paidion but what does the word "begetting" in this context mean to you?
The Greek word rendered as "beget" by the King James translators is "γενναω" (gennaO), a word from which we get the English word "generate" (or else we get it from the Latin "generatus" which is either derived from the Greek or both Greek and Latin derive it from some common root). The word "γενναω" is used in the geneology of Matthew 1, where Abraham begat Isaac, etc. (or one could say that Abraham generated Isaac).
When we beget or generate children, our children are human like us. We do not create them. When we create a picture, or building, or whatever, the thing created is unlike us and is not human.
God begat or generated His only-begotten Son as His first act. His son was divine like God. "He is the exact image of God's essence." (Heb. 1:3). God did not create His Son. Animals, trees, planets, stars, etc. which God created are unlike Him. They are not divine. (Although it is true that man, created in God's image, IS like Him in some respects.)
Interestingly enough, Jesus used this word with Nicodemus when He said, "You must be begotten again," or "You must be generated again," or "You must be regenerated." He did NOT say, "You must be born again," as is commonly thought. My view is that when we are regenerated, it is analogous to conception in the womb. It is only the beginning of life. Our lifetime of service to Christ is analogous to the growth of the baby in the womb, and our completion as children of God occurs in the resurrection, when we are born into the resurrection. This is our great hope. Paul said, " If the dead are not raised, 'Let us eat and drink, for tomorrow we die'.”
(1 Cor 15:32)
For whom He foreknew, He also pre-appointed to be conformed to the image of His Son, that He might be the firstborn among many brethren. (Rom. 8:29)
Here the word is "firstborn" nor "firstbegotten". In what way was Jesus "the firstborn among many brethren"? He was the first to have a true resurrection, to have an earthly body raised immortal. (All who are said to have been "raised from the dead" previous to Jesus were only resuscitated. They all died a second time.)
The "many brethren" will be all of His disciples whom He will "raise up at the last day." (John 6:40,44,54). And I understand Paul to say that it is necessary to be conformed to the image of the Son in order to be among these brethren.Thus when the many brethren are reborn into the resurrection, they will rejoice in Christ, but also in each other!
For what is our hope or joy or crown of rejocing in the presence of our Lord Jesus at his coming? Is it not you? (1Thess. 2:19)
That being said, the argument seems self-evident to me. The flaws you seem to see do not suggest themselves to me. My purpose for posting was not primarily to persuade, but to find holes in my argument. Your feedback has helped me sharpen my thoughts, thanks!