Original sin, the doctrine that when Adam the first man ate the forbidden fruit according to the first book of the Bible that this was a terrible sin that cut him off God and made us born in the same rebellious state.  This was supposed to be why we needed the atonement of Christ to make up for this so that we could be put right with God.  No good God would let us be born in such a state for he would want us to be with him in every moment of precious time.  The Church says that the human weakness in us is evidence for this original sin.  But it is just evidence for weakness and that is all.  God is universally insulted to justify the claim that nobody is saved without Jesus for all have descended from Adam and inherited his antagonism towards God like a virus.  

People took stories like Adam and so on literally in ages past.  Theologians today who say it is symbolic cannot give us a Bible verse that says it was.  They are making assumptions and treating them as the word of God.  To find absurdities and contradictions in the Adam story and claim that they indicate that the story is symbolically true but not literally true is extremely dishonest.  If we use that approach all the time we will have to start saying that every rubbish story say in paganism is true.  Adam did not exist so original sin is a lie.

The story says that Adam was asked not to touch the tree of knowledge of good and evil.  God made this law.  Touching the tree was not wrong in itself.  God made it wrong.  The story implies that sin is not exactly doing harm - it is the disobedience to divine authority that is the problem.  Original sin if it exists then causes the wish to unify law and morality in the name of God.

Theologians say that the tree was called the tree of knowledge of good and evil because anybody who touched the tree would know experientially what it is to stop being good and become evil.  They deny that Adam was going to get a purely intellectual knowledge of these things without experiencing them. 

Born again seems to differ according to religious persuasion.  To a Catholic it means the start of God deciding to have a loving relationship with you at baptism. To the Protestant it is the same thing but they often think it happens when you accept Jesus consciously as your substitute who earned salvation for you by paying for your sins for you. The term is terribly insulting to good people who are not believers for it implies that they are spiritually lacking and defective. It is really no better than racism especially when it teaches that people who have never heard the gospel will not be saved and will have to pay for their own sins in Hell. Even to suggest that God might find some other way to save them implies that they might not be saved and they might be ripe for Hell. That is nasty too.
The new birth allegedly removes original sin which causes our bias towards sin so it results in a holy life. Whether we are talking about born –again Protestants or Catholics most of them do not act in any remarkably virtuous way so the new birth is a conscious dose of quackery and deception. No concern is showing for proving that the baptism ritual actually helps. It is not about helping babies but about imposing the foolishness of religion on them.