You will not find scripture supporting the above.
When Adam disobeyed, he lost the absence of concupiscense.
So all of Adam's offspring were born with concupiscense...this is also called the sin nature...or the flesh.
We are all born with this sin nature which tends toward sin and does not consider God.
We are however guilty of our sins, as you've stated.
This is correct...but we are only guilty of our own sins.
I've provided sufficient scripture for this.
Romans 5:13----does not support your idea of imputation of Adam's sin.
I went through it verse by verse...
Agreed with 2 and 3. This is biblical theology.
I've never heard of 1 and you seem to be unable to provide any scripture for this idea.
Maybe you're just a big fan of Augustine.
We are born with the sin nature...
We are not born sinners.
To be a sin, we must be aware that we are sinning.
A baby and/or child does not know about sin.
They sin,,,but they cannot be held accountable for it because they are not aware of sinning.
At some point in their maturity, they become aware of sin, or are taught about it, and from that time
their disobedience to God's laws will become sin for them.
You're getting the SIN NATURE, CONCUPISCENSE, or THE FLESH -- conflated with sinning.
No adult believes they have never sinned (that I know of).
This is true,,,but for mature persons, as I've stated above.
Let me ask you this:
God told Cain that sin was crouching at the door ready to control him...
But Cain was told he must subdue sin and be its master.
Can a child subdue sin and be its master?
I have given Scripture and explanation.
(Rom. 5:12-14) does support the imputation of Adams sin to the human race. (5:12) declares it. (5:13-14) illustrates and explains it.
Babies don't have to know about sin to be born guilty of Adam's sin. It doesn't matter.
Whether a child or infant can subdue sin is immaterial to Adam's sin being imputed to the human race.
If you reject this imputation of Adams sin to the human race, then why do you accept the imputation of Christ's righteousness to the believer? If man was not imputed with Adam's sin, then every man is on his own. He is not a sinner until he sins. Christ cannot die for all in One Man if all are not guilty in one man. He can die for one. Who will it be...you maybe?