Dale, let's look at those verses you quoted, because I don't think they are saying what you think they are saying...
Behold, I was brought forth in iniquity, and in sin did my mother conceive me. (Psa 51:5 ESV)
This has to do with the mother, not the child. This indicates the condition of the child, but not the fault of the child.
The wicked are estranged from the womb; they go astray from birth, speaking lies. (Psa 58:3 ESV)
This is not in argument. What is in argument is whether or not, then, at that age (birth at least if not a few more years!), they can be accountable for what they are doing naturally, without any conscious decision to do so. I am not arguing that they are sinning, but they are sinning unconsciously and thus, as Paul says in Romans 7, sin, although there, is 'dead', or has no power to separate them from God at that point.
Why? Because Jesus paid the price for ALL sin, conscious and unconscious, for He was the one-time Sacrifice for all, as Hebrews states. If we look back in the OT, we will find that there were a special series of sacrifices for unknown and unintentional sins. So the babies and kids are covered and not yet dead in their sins, not yet separated from God. If they were, then Jesus lied when He stated that the children are His.
About Adam. My husband brought up something during one of his and my Bible studies here at home that deserves thinking about. God is clothed in light, right? Adam and Eve were first created in the image of God, and although we know that means having a spirit, might it also not mean that they, too, were originally clothes in something akin to the Shekinah glory? When Moses wanted to see God's glory and was only allowed to see the back of God in passing, his face was nevertheless shining and had to be covered for awhile to hide it from the Israelites. Adam and Eve walked with God. Did they not, too, shine just the way Moses did? And then, when they sinned, did that glory not depart from them? This would not, then, be self-centeredness to see that things were radically different...
Just something to think about.
Now, on to babies. First, can or do animals sin? No. Not at all. Nevertheless, they are 1) affected by the fact that we have sinned and 2) as infant (mammals are in my mind right now) have the instinct to survive by going for food and warmth and mommy. This is not selfishness. This is not sin. This is not self-centeredness in the way you seem to be presenting it. Babies -- human babies -- go for food and warmth and mommy, too, as a matter of survival. This is not a sin!
Then you quoted All we like sheep have gone astray; we have turned every one to his own way; and the LORD has laid on him the iniquity of us all. (Isa 53:6 ESV)
Absolutely. No argument. But the point is accountability, not wandering astray. Please note that Eve, adult though she was, is not the one through whom sin entered the world. Why? Because she was deceived. She was therefore not held responsible for ushering sin into the world even though she sinned. And sinned first.
And we have all gone astray. But there are those who lead and those who follow, first of all. Many of those who follow are deceived by those who lead. What is their position before God? Their sin is covered by Christ. We know that. As you quoted, the iniquity of us ALL has been laid on Him.
Something to think about.
You see, I have no argument with the fact that everyone is a sinner. The argument is whether or not that has caused their spiritual death, or separation from God, until such time as they know the law.
The argument is also that spiritual death is not spiritual unconsciousness. It has never been about the fact that we are all sinners.
By the way, you will note that the Jeremiah verse also mentions that the heart is sick, not dead.
One needs only become born again if one has died in sin. If one has become separated from God, then one needs to be brought back. Deliberate sin is what separates us. Our sin nature does not, or the children would not be the examples of 'such is the Kingdom of Heaven'. Babies have not yet died spiritually. They are not born dead in sin, for they have not yet sinned and are in no way responsible for the nature they are born with. A rat cannot help being a rat; a horse cannot help being a horse; a sparrow cannot help being a sparrow; and a human cannot help being a sinner.
Being a sinner, we will all go astray, even from birth. But that, according to Paul in Romans 7, is not what causes our spiritual death, or separation from God. He states clearly that without the law, sin is dead. Does that mean sin does not exist? Of course it exists, for we are all born with sin natures! What it does mean, however, that sin is powerless to separate the person from God. That is because Christ died for all those sins. It is only when the sin is deliberate in response to knowledge of the law (again, Romans 7) that the person is then separated from God spiritually, or becomes spiritually dead. How could Paul say it more clearly or plainly? "Once I was alive apart from law; but when the commandment came, sin sprang to life and I died." When he was first alive, he was still a sinner! But he was not yet separated from God!
Then the law came, or became known to him. It came into his life. Then his sin nature exerted itself, as it does with all of us at that time in our lives, and he deliberately and consciously obeyed his sin nature and disobeyed God. Then he was separated from God, and died spiritually.
He says that so clearly!
There is only one way to reconcile with God and from this sinfulness and that is through regeneration.
The only way that we are reconciled with God is through Christ Jesus. That is why children are not estranged from God yet. They stand reconciled at conception and do not die spiritually until they follow their sin natures deliberately. It is then that they must be born again, regenerated. They were generated by God from the first, and then need to be regenerated when they die spiritually. Yes they are born sinners, but Jesus died for them, too, and they have not yet consciously sinned.
Please, please notice I am not claiming righteousness for anyone apart from Christ. In fact that was one of my points in the Gospel in the Stars argument! I am not claiming life for anyone apart from Christ. I am not claiming that anyone is not a sinner.
I am claiming that Paul said we are alive spiritually before the law causes our sin natures to intentionally disobey, giving sin, finally, the power to estrange us from God, which is spiritual death.
Thus, while all sin, intentionally or unintentionally, sin is not given the power in a person to cause spiritual separation from God until the law is known.
Thus, and finally, to get back to the topic of the thread, we hold no culpability for sin unknown to us, even though we are sinners. We also are not responsible for the sin of others unless we did something to encourage or support that sin or did not attempt to stop it when we could have.