Therefore the LORD God sent him forth from the garden of Eden, to till the ground from whence he was taken. So he drove out the man; and he placed at the east of the garden of Eden Cherubims, and a flaming sword which turned every way, to keep the way of the tree of life.
For since by man came death, by man came also the resurrection of the dead. For as in Adam all die, even so in Christ shall all be made alive.
Part of understanding what it means for us to be sinners is to look at what is meant by Paul when he writes "by one man's disobedience many were made sinners, so by the obedience of one shall many be made righteous" and David when he writes in the Psalms "Behold, I was shapen in iniquity; and in sin did my mother conceive me".
When God made Adam, Adam was made in God's own image and likeness and God placed him inside the garden of Eden and formed Eve from Adam's rib. It was man's place to be the caretaker over the garden and the animals and to live in communion with God as the source of life. God told Adam to eat from any tree in the garden except the tree of knowledge of good and evil, and warned him "for in the day that thou eatest thereof thou shalt surely die". Being deceived by the lie from the serpent that "then your eyes shall be opened, and ye shall be as gods, knowing good and evil", Adam and Eve ate from the tree. They went from looking to God as their source of life and identity to looking to the created things of this world to give them life and to make them like God. Their first reaction was to see themselves as naked and, being ashamed of what they had done, to hide from God. God told Adam "cursed is the ground for thy sake" and "In the sweat of thy face shalt thou eat bread, till thou return unto the ground; for out of it wast thou taken: for dust thou art, and unto dust shalt thou return" as the consequences of his actions and placed Adam and Eve outside of the garden. But hope for the future of mankind was given in what God told the serpent "And I will put enmity between thee and the woman, and between thy seed and her seed; it shall bruise thy head, and thou shalt bruise his heel", in reference to the Messiah as it is written "Forasmuch then as the children are partakers of flesh and blood, he also himself likewise took part of the same; that through death he might destroy him that had the power of death, that is, the devil; And deliver them who through fear of death were all their lifetime subject to bondage".
So now mankind, originally created for life in union with God taking care of God's creation, is seperated from God, subject to death, and looking to the created things of the world for life. This disordered nature that was brought about by the fall was transmitted to the entire human race, as it is written that Adam "begat a son in his own likeness, and after his image; and called his name Seth" and "Wherefore, as by one man sin entered into the world, and death by sin; and so death passed upon all men, for that all have sinned".
The physical effects of the fall include being subject to corruption and death and having bodily desires disordered. There are lines in the Psalms reflecting this in our bodies such as "I am afflicted and ready to die from my youth up" and "My days are like a shadow that declineth; and I am withered like grass". And Paul writes "But I see another law in my members, warring against the law of my mind, and bringing me into captivity to the law of sin which is in my members". And not just the human race, but also the creation that mankind was intended to be the head of as Paul writes "For we know that the whole creation groaneth and travaileth in pain together until now. And not only they, but ourselves also, which have the firstfruits of the Spirit, even we ourselves groan within ourselves, waiting for the adoption, to wit, the redemption of our body". We await the undoing of this at the return of Christ when "the heavens being on fire shall be dissolved, and the elements shall melt with fervent heat?" and "we, according to his promise, look for new heavens and a new earth" accomplished by the power of His own resurrection from the dead. This is why Jesus said "I am the resurrection, and the life" and it is written "So when this corruptible shall have put on incorruption, and this mortal shall have put on immortality, then shall be brought to pass the saying that is written, Death is swallowed up in victory", that Christ "shall change our vile body, that it may be fashioned like unto his glorious body, according to the working whereby he is able even to subdue all things unto himself", and "Knowing that Christ being raised from the dead dieth no more; death hath no more dominion over him". Jesus, as the author and source of life, had to be crucified and raised from the dead in order to restore us to life because we are unable to do it ourselves as the Psalms say "What man is he that liveth, and shall not see death? shall he deliver his soul from the hand of the grave?".
While we await the resurrection of the body, we are given the opportunity in this lifetime to have our spirit renewed in Christ by being baptized into His death and raised up in newness of life, and to repent of our sins and be conformed to Christ. It is in Christ that we are united with God as He Himself said "I am the door: by me if any man enter in, he shall be saved" and "I am the way, the truth, and the life: no man cometh unto the Father, but by me". It is in baptism that we are born from above after being buried in the likeness of Christ's death. This is why it is written "For ye are all the children of God by faith in Christ Jesus. For as many of you as have been baptized into Christ have put on Christ", "There is one body, and one Spirit, even as ye are called in one hope of your calling; One Lord, one faith, one baptism, One God and Father of all", and "The like figure whereunto even baptism doth also now save us (not the putting away of the filth of the flesh, but the answer of a good conscience toward God,) by the resurrection of Jesus Christ". It is in baptism that we are received into God's covenant as His people as it is written "In whom also ye are circumcised with the circumcision made without hands, in putting off the body of the sins of the flesh by the circumcision of Christ: Buried with him in baptism, wherein also ye are risen with him through the faith of the operation of God, who hath raised him from the dead". But baptism is not the end of Christian life, but the beginning, where we are introduced to having a right relationship with God that must be continued in through daily self examination and repentence, walking in the Spirit, bearing the fruit of the Spirit, and struggling against the lusts of the flesh in order to grow and mature in becoming conformed to Christ. We are to do this in this life because it is written that all "shall come forth; they that have done good, unto the resurrection of life; and they that have done evil, unto the resurrection of damnation" and "For he that soweth to his flesh shall of the flesh reap corruption; but he that soweth to the Spirit shall of the Spirit reap life everlasting".
Having been buried with Christ by baptism into His death, that as He was raised from the dead so I could be made to walk in newness of life, may God let me not be conformed to this world, but transformed by the renewing of my mind.