Origin of Sin

Man’s First Sin.
The first sin of our first father is found described in Gen. 3:1–7 in words which are familiar to every one. This narrative has evidently some of that picturesque character appropriate to the primeval age, and caused by the scarcity of abstract and definite terms in their language. But it is an obvious abuse to treat it as a mere allegory, representing under a figure man’s self–depravation and gradual change: for the passages preceding and following it are evidently plain narrative, as is proved by a hundred references. Moreover, the transactions of this very passage are twice referred to as literal (2 Cor. 11:3; 1 Tim. 2:14), and the events are given as the explanation of the peculiar chastisement allotted to the daughters of Eve.

Unbelief Its First Element.
The sin of Adam consisted essentially, not in his bodily act, of course; but in his intentions. Papal theologians usually say that the first element of the sin of his heart was pride, as being awakened by the taunting reference of the Serpent to his dependence and subjection, and as being not unnatural in so exalted a being. The Protestants, with Turrettin, usually say it was unbelief; because pride could not be naturally suggested to the creature’s soul, unless unbelief had gone before to obliterate his recollection of his proper relations to an infinite God; because belief of the mind usually dictates feeling and action in the will; because the temptation seems first aimed (Gen. 3:1) to produce unbelief, through the creature’s heedlessness; and because the initial element of error must have been in the understanding, the will being hitherto holy.

If Volitions Are Certainly Determined, How Could A Holy Being Have This First Wrong Volition?
How a holy will could come to have an unholy volition at first, is a most difficult inquiry. And it is much harder as to the first sin of Satan, than of Adam, because the angel, hitherto perfect, had no tempter to mislead him, and had not even the bodily appetites for natural good which in Adam were so easily perverted into concupiscence. Concupiscence cannot be supposed to have been the cause, pre–existing before sin; because concupiscence is sin, and needs itself to be accounted for in a holy heart. Man’s, or Satan’s, mutability cannot be the efficient cause, being only a condition sine qua non . Nor is it any solution to say with Turrettin, the proper cause was a free will perverted voluntarily. Truly; but how came a right will to pervert itself while yet right? And here, let me say, is far the most plausible objection against the certainty of the will, which Arminians, etc., might urge far more cunningly than (to my surprise) they do. If the evil dispositions of a fallen sinner so determine his volitions as to ensure that he will not choose spiritual good, why did not the holy dispositions of Adam and Satan ensure that they would never have a volition spiritually evil? And if they somehow chose sin, contrary to their prevalent bent, why may not depraved man sometime choose good?

Answer.
The mystery cannot be fully solved how the first evil choice could voluntarily arise in a holy soul; but we can clearly prove that it is no sound reasoning from the certainty of a depraved will to that of a holy finite will. First: a finite creature can only be indefectible through the perpetual indwelling and superintendence of infinite wisdom and grace, guarding the finite and fallible attention of the soul against sin. This was righteously withheld from Satan and Adam. Second: while righteousness is a positive attribute, incipient sin is a privative trait of human conduct. The mere absence of an element of active regard for God’s will, constitutes a disposition or volition wrong. Now, while the positive requires a positive cause, it is not therefore inferable that the negative equally demands a positive cause. To make a candle burn, it must be lighted; to make it go out, it need only be let alone. The most probable account of the way sin entered a holy breast first, is this: An object was apprehended as in its mere nature desirable; not yet as unlawful. So far there is no sin. But as the soul, finite and fallible in its attention, permitted an overweening apprehension and desire of its natural adaptation to confer pleasure, to override the feeling of its unlawfulness, concupiscence was developed. And the element which first caused the mere innocent sense of the natural goodness of the object to pass into evil concupiscence, was privative, viz., the failure to consider and prefer God’s will as the superior good to mere natural good. Thus natural desire passed into sinful selfishness, which is the root of all evil. So that we have only the privative element to account for. When we assert the certainty of ungodly choice in an evil will, we only assert that a state of volition whose moral quality is a defect, a negation, cannot become the cause of a positive righteousness. When we assert the mutability of a holy will in a finite creature, we only say that the positive element of righteousness of disposition may, in the shape of defect, admit the negative, not being infinite. So that the cases are not parallel: and the result, though mysterious, is not impossible. To make a candle positively give light, it must be lighted; to cause it to sink into darkness, it is only necessary to let it alone: its length being limited, it burns out.

~ R.L. Dabney, Systematic Theology, Section Three—The Condition of Man, Chapter 29: The Fall and Original Sin