Oh, it's very different, because you (and many others) believe Adam had a different nature than Abraham. God is wiser than man, and so he made it clear that Jesus had the same nature as Abraham, a man born after the "so called" fall.
I don't know that I have ever stated Adam had a different "nature" before or after the fall. Only that the nature Adam had after the "eyes were opened" was no longer pure and undefiled. Adam was defiled, Abraham was defiled. The seed that anointed Mary's egg (to be rather graphic) was not of Adam nor of Abraham, but of the Word of God. In that conception, it follows that Christ was as the Eden Adam (before the fall) in that the human nature of Christ was without sin, capable of being tempted to sin (just as Adam was when presented the fruit by Eve), but remained undefiled to the cross.
All men are born upright just as Adam was created, but all men sin just as Adam sinned. Jesus came in this same nature that could be tempted (God cannot be tempted- Jam 1:13), yet he never sinned.
Men are not born sinners, men are not born separated from God, but all men sin and become separated from God.
This would only matter if one could in fact live without ever committing a sin. Because, "all men sin" then really the point isn't really that important to the OP. If the topic were on the condition in which all are born, then it would be of substance to the OP to contend for one side or the other.
That all have sinned is important. Just exactly when all men have sinned is relatively minor unless one is attempting to live sinless - perfect, or desire to contend that a person could live from birth, sinless.
1 Pet 2:25 For ye were as sheep going astray; but are now returned unto the Shepherd and Bishop of your souls.
If man was born separated from God, then it could never be said he is RETURNED to God, but that is exactly what Peter said.
Peter is quoting from Isaiah. "All we like sheep have gone astray; we have turned every one to his own way; and the LORD hath laid on him the iniquity of us all."
In the 1 Peter passage, Peter is not addressing the unregenerate, he is spending the words to encourage the assembly folks to servitude and to "follow in His steps."
What you seem to desire is to apply "returned" to the unregenerate. If that is the case, then it would further validate the view that God determines the salvation of every one that is to "return" and to be saved. That seems to be the opposite of what your view has been on the BB.
Notice the use of the words "bishop of your souls." The application (using your view) would be that the unregenerate "return(ed)" to God (some of the regenerate) because He was the "bishop of their souls," and it follows then that those not "returned" then God was not the "bishop of their souls."
Again, no matter which way you read the verse, it validates a view that you stated you don't hold.
Because people believe Augustine's false doctrine, they must deny that Jesus came in the flesh and had the same nature as man. They must invent fantastic superstitions like the Immaculate Conception. False doctrine such as Total Inability originated in this false doctrine. The belief that babies had to be baptized to wash away Original Sin came from this doctrine.
Jesus was born upright, just as all men are born upright. The difference is that we have all sinned and become sinners, Jesus never sinned.
The Immaculate Conception (the thinking that Mary was "sinless and kept from sin at conception) is certainly a false doctrine.
I don't agree with all that Augustine taught, nor some of his life choices. The same as I don't agree with all anyone has taught or some of their life choices.
Total inability is problematic to you, but that isn't important at this point.
The baptism of infants was a human invention (same as the SBC view of age of accountability making children "safe" until some maturation understanding) and served the people even to this day. Again, it is of little matter in the long run.
I don't think you would teach that an infant busts hell wide open if they die. Fear drives people to look for validation of that principle, and because the Scriptures do not directly address the issue, it remains a matter of opinion and preference as to what makes the child "safe."
Lastly, I would suggest that your use of "born upright" is a bit of a problem in balance with the rest of the use of the word "upright" in the Scriptures.
Micah 7 speaks that the "upright" do not exist on the earth.
Isaiah 26 speaks of the "most upright" (God) bring ruin and weighing the path of the just.
Your reference to Ecclesiastes 7 is the desire by the writer to find a man or woman of uprightness; he found none and acknowledge that God makes one upright; and that uprightness is not found outside the purposed work of God.
Given just those few selections of the word "upright," it shows that you have perhaps mistaken the use and the appropriate application.
