3.1 "God from all eternity, did, by the most wise and holy counsel of His own will, freely, and unchangeably ordain whatsoever comes to pass; yet so, as thereby neither is God the author of sin, nor is violence offered to the will of the creatures; nor is the liberty or contingency of second causes taken away, but rather established."
From this link I get an answer (which I hope I'm not mistaken the answer) that before Adam and Eve exist on earth (including before they eat the fruit), either both of them already destined for heaven or both of them already destined for hell or one of them already destined for heaven.
but you must not eat from the tree of the knowledge of good and evil, for when you eat from it you will certainly die.
Assuming that the word "die" means "die spiritually" I put like this :
A. Before He create Adam and Eve - before Adam and Eve eat the fruit, God destined each human (including Adam and Eve) who will exist on earth will die spiritually.
IF God's Original Sin is in the time-frame AFTER Adam eat the fruit, then "die spiritually" can not be like point-A. So, the one which "fit" with God's Original Sin is :
B. Before He create Adam and Eve - before Adam and Eve eat the fruit, God destined that : IF Adam eat the fruit THEN each human (including Adam and Eve) who will exist on earth will die spiritually.
To me, if it's about baby Cain/Abel/Seth, then point-B "fits" with God's Original Sin. So, it's certain that when those babies will be born, they are already in "die spiritually" condition and the election can happen from a situation like that. One is elected from those who "already" die spiritually. So, the one who is not elected goes to hell.
But if Adam and Eve already destined beforehand (as to me that's the answer to the question before), my own conclusion is :
then there is no Original Sin, because the election itself is not based on any kind of act (including break His Law such as Adam eat the fruit) - but from Adam, Eve, Cain, Abel, Seth (before they exist, before they do anything - before they are in a die spiritually condition) either all the five of them destined to hell or all the five of them destined to heaven or some of them destined to heaven and the rest destined to hell.
So my question is : From what kind of condition of Adam and Eve (before they exist - before they eat the fruit - before they die spiritually) when they are elected ?