Well, that is not what the scriptures say. The scriptures say God has made man upright, but they have sought out many inventions.
Ecc 7:29 Lo, this only have I found,
that God hath made man upright; but
they have sought out many inventions.
The word "they" is plural and points back to the word "man" showing this verse is speaking of ALL men, not just Adam.
So we are not conceived in a sinful condition as you believe, we are conceived in an UPRIGHT condition.
We are not separated from God either, Jesus shows three times in Luke 15 that sinners are not originally lost.
Luke 15:4 What man of you,
having an hundred sheep, if he lose one of them, doth not leave the ninety and nine in the wilderness, and go after that which is lost, until he find it?
The shepherd originally had 100 sheep, not ZERO as your belief would conclude. One sheep BECAME lost, but he was not originally lost.
Luk 15:8 Either what woman having ten pieces of silver, if she lose one piece, doth not light a candle, and sweep the house, and seek diligently till she find it?
The woman originally had 10 pieces of silver, not ZERO as would be the case if Original Sin is true. One piece later BECAME lost.
Luke 15:11 And he said,
A certain man had two sons:
Jesus said the father originally HAD TWO SONS. The prodigal son was not born lost and separated from his father as you falsely teach.
You got this correct, Romans 9:11 shows babies have not done any evil and are not sinners.
Rom 9:11 (For the children being not yet born, neither having done any good or evil, that the purpose of God according to election might stand, not of works, but of him that calleth; )
Because of Adam's sin, all men were barred from the tree of life and thus physically die, but men spiritually die when they come to know right from wrong and personally sin.
Rom 7:9 For I was alive without the law once: but when the commandment came, sin revived, and I died.
10 And the commandment, which was ordained to life, I found to be
unto death.
11 For sin, taking occasion by the commandment, deceived me, and by it
slew me.
The Jews did not believe a person became accountable for sin until a certain age and level of maturity. The words Bar Mitzvah (men) and Bat Mitzvah (women) mean "son of the commandments" or "daughter of the commandments" meaning a child has become an agent who is subject to the law.
http://en.wikipedia.org/wiki/Bar_and_Bat_Mitzvah
This is exactly what Paul is describing in Romans 7. When he came to know the law, he believed the law would lead him to life, but sin taking occasion by the law convicted him as a sinner and he spiritually died.
If we are born dead in sin as you falsely teach, then Paul could never say he was ALIVE, but that is exactly what Paul taught.
All men's sins were paid for by Jesus when he shed his blood on the cross, but we do not receive this payment unless we believe on Jesus as God has commanded. All men who place even the smallest amount of faith in Jesus (as a mustard seed) will be saved, Jesus will not cast out any person who comes to him in faith under any circumstance.
Jhn 6:37 All that the Father giveth me shall come to me;
and him that cometh to me I will in no wise cast out.
Jesus will not cast out some who come in faith as you imply over and over again.