Many thanks for addressing this objection, which allows me to stress something that apparently (and astonishingly) remains unnoticed:
If one understands “original sin” as “state with propensity to sin (anger, envy, lust, greed, hate, etc.)” and “state of being in need of redemption”, the teaching pervades the whole Bible. The first passages supporting this teaching, and in fact the very biblical foundation of it, are undoubtedly Genesis 3-4 : The narratives of the sin by Adam and Eve, and the sin by Cain.
Genesis 3-4 displays a clear difference between the way how Adam and Eve come to disobey God’s commandment, and the way how Cain follows the urge to murder Abel:
In the account of Adam and Eve, the snake astutely designs its question to lure innocent Eve into a deceitful dialogue: “Has God really said you must not eat from any of the trees in the garden?” (Genesis 3:1). Then the snake tempts Eve with these words: “You will not certainly die,” the serpent said to the woman. “For God knows that when you eat from it your eyes will be opened, and you will be like God, knowing good and evil.” (Genesis 3:4-5)
The core of the temptation is the proposal to usurp God’s supremacy and mistrust God. And the fall initiates when Eve indulges in pondering this proposal. The covetousness of the fruit (concupiscence) appears only thereafter. The transition is from a state of total innocence to mistrusting God and rebellion.
I quote from my paper referred in your comment (Section 5):
“The way the temptation progresses unveils the structure of the primeval human psyche: Eve was endowed with spiritual force to master concupiscence to the extent that it had been silly on the part of the snake to try to seduce her by praising the sensual beauty of the forbidden fruits. Instead the snake astutely challenges Eve’s fidelity to God. However, as soon as Eve begins to doubt, the concupiscence emerges, and the woman by herself (without any insinuation on the part of the snake) sees that the tree is “good to eat”, “a delight to the eyes”, and “desirable”. Gordon Wenham brilliantly comments: “The woman’s covetousness is described in terminology that foreshadows the tenth commandment” (Wenham, Word Biblical Commentary: Genesis 1-15, 1987, p. 75).”
After their fall Adam and Eve are not immediately killed by God and doomed to hell. God gives them opportunity to repent and allows them to remain on earth, but “outside the garden”: suffering the effects of their sin and submitted to concupiscence, that is, propensity to sin engrained in their carnal condition.
By contrast, in the account of Cain and Abel, propensity to sin (in form of envy, anger, and hate) is present since the very beginning of the temptation, whereas “being like God”, reaching God’s supremacy, dos not appear in the narrative at all:
On the one hand, in Genesis 4:5 Cain is portrayed as being “very angry” (in the Bible often a prelude to homicidal acts). On the other hand, in Genesis 4:7 God attempts benevolently to provoke a change of heart in Cain: “ Why are you angry and why has your face fallen? Is there not forgiveness, if you do well? And if you do not well, sin is crouching at your door; its urge is for you, but you must rule over it.” (see Wenham 1987, p. 104-105). God’s words stress that Cain shares a strong passion, but can rule over it and find relief (“forgiveness”), not from the not-yet-perpetrated sin, but from jealousy, if he only wants to.
Interesting is the comparison between “its urge is for you” in Genesis 4:7, and “your urge will be to your husband, but he shall rule over you” in Genesis 3:16. The same word “urge” is used for a “sexual urge” that lures the woman to a slaving dependence in the state after the fall, and the “ urge to get rid of the brother” that will prompt Cain to murder Abel.
In Adam and Eve sin gives birth to the state of concupiscence; in Cain the state of concupiscence gives birth to sin .
This very teaching is magnificently summarized in the letter of St. James 1:15:
“Then, after desire has conceived, it gives birth to sin; and sin, when it is full-grown, gives birth to death.”
Another quite relevant aspect in Genesis 4 is highlighted by the expression “couching at your door” . The strong propensity to sin growing in Cain’s heart is described like a wild beast on Cain’s doorstep looking to devour him. The comparison astonishingly supports the often promoted interpretation that the concupiscence referred to as a consequence of “original sin” consists in the selfish Darwinian tendencies enhanced by human intelligence and will. “There is virtually no known human behaviour that we call ‘sin’ that is not also found among nonhuman animals.” (Domning 2001) In this sense what is described in Genesis 4 is nothing other than the description of the human condition as it would result from Darwinian behavioral patterns responsible for evolution. Cain’s selfish jealousy is engrained in Cain’s evolved animality.
In summary, the narratives in Genesis 3 and 4 clearly support the following tenets:
God created the first image bearers in “the state of original innocence”, endowed with special grace to offset propensities to sin coming from envy, lust, greed, anger, fear etc., and therefore they were not in need of redemption.
By contrast after the sin of Adam and Eve, i.e.: the first human sin (not necessarily the first sin of the first human bearers), the propensity to sin is present in all human beings, including children, even before they themselves perpetrate a sin, and therefore they all are in need of redemption.
This teaching of the Old Testament is reinforced in the New Testament:
So for instance, the apostle Paul confirms tenet 2 in Romans 5:19
For as through the one man’s disobedience the many were made sinners, so also through the obedience of the One the many will be made righteous.
And in Romans 11:32 St. Paul enounces a principle which may be considered the reason of why God consents in extending the propensity to sin to the whole human kind (tenet 2):
For God has shut up all in disobedience, so that He may show mercy to all.
One could object that, if this is the case, God should have created Adam and Eve WITH propensity to sin (in contradiction to tenet 1 above). Nonetheless, as Christy very well states:
God’s initial plan was incarnation, not redemption. For this reason, God created the first image bearers free from any sinful propensity (anger, jealousy, envy, lust, etc.), so that “their choice to sin would be a move from total innocence to rebellion”, as in fact it was.
Finally, Hebrews 7 can be interpreted as backing tenet 1 above as well.