What exactly is this “save” stuff?
When Adam fell into sin, the result was every one of his descendants also being “infected” with his spiritual DNA, the sin nature. David mourned this fact in Psalm 51:7 Tanakh (Psalm 51:5 OT.) “Behold, with iniquity I was formed, and with sin my mother conceived me.” This does not mean that his mother bore him illegitimately. His mother had inherited a sin nature from her parents, and they from their parents, and so on. David inherited this from his parents, just as we all do.
Even if we live as “upright” and “good” a life as possible, every single thing we do is out of the body of a sinner as a result of the inherited sin nature.
Job 14:4 “Who can bring a clean thing out of an unclean one? Not one.” Job 15:14-16 “What is man that he should be innocent, and that one born of woman should be just? Lo! He does not believe in His holy ones, and the heavens are not pure in His eyes. Surely [not] one who is abominable and impure, a man who drinks injustice like water.” Job 25:4 “How then can man be just with God, and how can one born of woman be clean?” Psalm 14:2-3 “The Lord in Heaven looked down upon the sons of men to see whether there is a man of understanding, who seeks the Lord. All have turned away; together they have spoiled; no one does good, not even one.”
Eternal death is the only just punishment for sin. That is why we need to be saved, we need a savior (Isaiah 1:18.)