I have been reading Terryl L Givens's most recent scholarly book about Mormonism - Wrestling the Angel - The foundations of Mormon thought: Cosmos, God, Humanity (Oxford University Press, 2015), and my verdict is that the book is simply superb.
By my evaluation; Givens is one of the most sheerly intelligent writers alive, and also a man whose thought processes and evaluations are extremely congenial to me - he is 'on my wavelength' in an intellectual sense, and has a similar set of priorities in the domain of theology and religion.
In general, I find Givens's account and explication of Mormon theology to be completely satisfying; the exception is The Atonement, the various theories of which he explores in a useful and thorough fashion, before concluding that (as a statement of fact) there is no satisfactory and comprehensive Mormon theory of the Atonement - its importance is central to modern Mormonism, but its nature and operations are essentially regarded as a mystery.
While I hope that this suffices for most people, I am continually 'bugged' by a personal need to understand - or at least know more about - the nature of the Atonement; and having finished Givens's book I felt that for the first time I may be able to articulate a theory which satisfies me - which, in other words, satisfies the constraints I understand to be necessary for an adequate theory from a Mormon metaphysical and theological perspective.
In a nutshell, this theory is the idea that Christ's Atonement was about repentance, rather than sin as such; and that Christ's sufferings (in the Garden of Gethsemane and on The Cross) were a suffering of the agonies of repentance for Man - rather than a suffering of the sins of Man.
By his Atonement, therefore, Christ enabled all Men to repent and be saved - by the simple (and 'easy') act of accepting Christ's supreme act of vicarious repentance - this replacing the 'impossible' demand of Men to repent each and every one of their sins individually and wholly.
How do I get to this theory?
The basic 'set-up' is my conviction that human agency (or free will - the ability of all men to be a 'first cause' or 'unmoved mover' - i.e. genuinely to choose from within ourselves and not as a consequence of prior causes) is due to our eternal pre-mortal existence and primary autonomy.
In other words Human agency is not from God, not a gift from God - it is a given fact of reality; which God must work-around, and which God cannot overwhelm or obliterate (even if He wanted-to - which I do not think he does).
Agency just is a fact of existence.
So the Atonement takes place against a back-drop of ineradicable agency - God's 'problem' was to advance Men towards divinity in this context. It seems that incarnation and mortality are absolutely necessary for Man to make spiritual progress towards divinity - therefore I infer that the single most important thing about incarnate life is death.
Death is the gateway to incarnate immortality.
I accept that we all, as pre-mortal spirit, volunteered to undergo life on earth and death. But the big problem anticipated for this 'plan' would have been that mortal life of earth entails sin (we are too weak, temptations too numerous and strong), and sin renders us unfit for resurrection to immortality.
(If we - as we are in mortal life - were resurrected to immortality, then that would be a kind of Hell; to benefit from resurrection our souls must be purified and our bodies perfected and yet we remain our-selves - and this process of pre-resurrection purification and perfection can only be done with our consent.
This is salvation - being saved to eternal life ('life' referring to incarnate immortality, as our-selves).
Resurrection to happiness depends on repentance - and that is all it depends upon.
My understanding is that nobody - none of the pre-mortal spirits which we were - would be so reckless and foolish as to volunteer to risk mortality under such difficult conditions unless there was special provision that salvation would be easy and straightforward.
If our individual salvation required recognition, acknowledgement and repentance of every single sin; then salvation would be a rare occurrence - perhaps nobody would ever be saved.
Thus, provision was made that mortal men should be saved by the vicarious Atonement of Jesus Christ - He would save us; and all that each of us would need to do would be freely to choose to to accept Christ's act on our behalf.
So the divine Son of God was incarnated and died - and by this account Christ's death was the single most important thing he did; but his death would not have been efficacious unless he had also performed the Atonement; and the Atonement must be about repentance.
Without Christ's Atonement, repentance would be de facto impossible - since there is too much to repent, and because our knowledge of what needs to be repented is partial and distorted.
So, as mortals, we could never know the full extent of our transgressions - and therefore we would not even know what had to be repented.
And while we were 'working through' discovering and understanding all the multitude of things that needed repenting, then we would be accumulating more sins...
Because the nature of repentance is recognition and acknowledgement - repentance is knowing that we have objectively sinned which is vital; and knowing how so many of our attitudes and actions are at-odds-with the divine plan.
In a nutshell, full repentance requires a full knowledge of reality, and knowledge of our denials of reality (denials by thought and deed).
Since this is impossible, it can only be done for us. And it was done, by Christ's Atonement.
I take it as axiomatic that for a Christian, Christ's Atonement must be absolutely necessary. That is, necessary to the salvation of Men.
Since repentance is a psychological act; then this psychological act must be made effective.
Since specific repentance for each and every sin is impossible, effective repentance absolutely requires that repentance be simplified to a single decision that encompasses all other decisions.
It was Christ's Atonement that made repentance into a single decision.
My understanding is that before He died, Christ repented all the sins of everyone who had lived and died up to that point - all who lived before Him - and it was the pain of this vast act of Atonement which he apparently underwent mainly in Gethsemane and on The Cross.
After His death and resurrection, Christ continued, and He continues, to repent the since of all who lived and died after He did, and those live and die now - and He continues to suffer for that reason.
So Christ's Atonement made effective repentance possible - from this act, we may by a single choice accept that God loves us, that He is wholly good; and that God's plans are for our benefit - and by repentance we permanently ally ourselves with these plans.
The Atonement gave mortal life on earth a fail-safe mechanism.
This was necessary.
Many or most - or perhaps all - people who are incarnated as Men, and who volunteered to be incarnated as Men, lead terrible lives which render them in need of repentance on an epic and virtually impossible scale.
But this need will have been fore-known, and our Loving Father who wants everyone to be saved (that is, everyone who will consent to be saved - He cannot force anyone to be saved - nor would He wish to compel them even if He could)... our Loving Father made provision for this outcome; so that we would be saved anyway by the shortest and simplest and most-accessible of acts: the simple acceptance of the gift of full-repentance which Christ did for us, and which He offers to give us.
Because of the Atonement we have nothing more to do than recognise the nature of this gift and accept it; and our reward is the happiness of eternal incarnate life as our-real-selves (with a purified soul in a perfected body).
Even the weakest person born into the worst circumstances can achieve this acceptance of a gift - when each of us was and will be presented, after death, with a restoration of our pre-mortal state of full understanding of the divine plan.
Of course, we will (as free agents) be able to reject this gift - and to choose damnation.
This is why mortal incarnate life was and is a real risk, and why it was essential that all who underwent it (all of us,that is) were volunteers who knew the risks.
Mortality offers the possibility, even the probability, of spiritual progress towards divinisation; it also contains the ineradicable risk that at the end of it all, we might reject salvation and damn-ourselves.
Our loving Father would not have set up this plan of salvation unless the odds of salvation were stacked in our favour; so the odds are indeed stacked in our favour - and to do this was the work of Christ's Atonement.
But no matter how favourable the odds of salvation - salvation cannot be guaranteed, because of the primary reality of agency.