14 For if ye aforgive men their trespasses, your heavenly Father will also forgive you: 15 But if ye aforgive not men their trespasses, neither will your Father forgive your trespasses.
This post answers the question, "Why must I forgive others their trespasses in order to secure God's forgiveness of my trespasses?"
One answer could be merely because God says so. I don't know that this answer is wrong. However, it may be wrong or, at the least, incomplete. The answer I give involves the resolution of a fundamental tension in the mechanism underlying application of the atonement. We are taught that Christ is "standing betwixt them and justice; having broken the bands of death, taken upon ahimself their iniquity and their transgressions, having redeemed them, and bsatisfied the demands of justice" and that " God himself aatoneth for the sins of the world, to bring about the plan of bmercy, to appease the demands of cjustice, that God might be a dperfect, just God, and a emerciful God also." Thus it seems that Christ's suffering pays the price for our sins. This principle is neither new nor earth shattering.
However, though these scriptures show how the price was paid, there remains another demand of justice. Justice requires not only that the price be paid, but that it be paid by the transgressor!
11 Now there is not any man that can sacrifice his own blood which will atone for the sins of another. Now, if a man murdereth, behold will our law, which is ajust, take the life of his brother? I say unto you, Nay.
I have seen two candidate work-arounds that purport to resolve this tension. Though neither may prove the case, both are related to the requirement that the atonement be infinite: "not a bsacrifice of man, neither of beast, neither of any manner of fowl; for it shall not be a human sacrifice; but it must be an cinfinite and deternal esacrifice."
1) At-one-ment is the first work-around. The idea that you and Christ become one, such that the punishment justice requires that you experience can go to Christ since the two of you are now one. Much as it's just to flog a thief's back for the crimes of his hand, because the thief is a single entity- so becoming one with Christ allows Him to be wounded for our transgressions, thus fully satisfying justice. The sacrifice must be infinite because either A) were there any end to the two of you being one, justice would still require a narrowly tailored punishment to the more culpable member, or B) only an infinite sacrifice could bind a mortal and an immortal such as you and Christ.
2) The second work around is the idea of basically getting all of creation to "look the other way." First, let's look at the relevant stakeholders when you sin. Who is harmed, and who can forgive those harms? God, ourselves, the earth, and each other come to mind as harmed entities. Also, every intelligence which has a sense of justice will have that sense offended if the sinner is not justly punished. Let's take each stakeholder class in turn.
-God: He can forgive of his own volition the harm against Him. It seems He usually does so.
-Ourselves/each other: We, like God, can forgive or refrain from forgiving, harms against ourselves. This includes self-inflicted and externally-inflicted harms. More on this category below.
- Earth: I'll lump the earth in with all non-sinning, justice-capable intelligences, which I now address. Presume every creation of God has intelligence. Those creations which have a sense of justice, which sense of justice would be offended if God did not punish sinners for their sins, must also have a sense of mercy (why these senses must be paired I have yet to establish- for the moment presume if a creation has the one, it also has the other). Well then, perhaps God persuades all these intelligences to fire their mercy neurons (remember, justice and mercy are here depicted as senses) to the exclusion or at least overpowering of their justice neurons. Perhaps their compassion at viewing the immeasurably torturous atonement (presuming they have a compassion sense, which isn't asking much presuming the senses of justice and mercy already) moves them to refrain from demanding justice. Only a being as great as Christ suffering to the extent He did would be sufficient to cause all of these innocent intelligences to be so moved (hence the requirement of infinite sacrifice). Under this work-around, the requirement of forgiveness makes the most sense. You must forgive others their trespasses against you, like these intelligences voluntarily "forgave" an offended sense of justice and, because of God's sacrifice, embraced mercy, allowing you to forever escape punishment. By a similar principle you must be willing to forgive for the Atonement to work in your case.
But what if you refuse to forgive another's trespasses, but instead insist that justice extract the uttermost farthing from him or her? Ironically, it is you that is punished for the greater sin: "34 And his lord was wroth, and delivered him to the tormentors, till he should pay all that was due unto him.
I'm not sure how the second work-around accounts for that comeuppance. Sorry to leave you with an unanswered question.
35 So likewise shall my heavenly Father do also unto you, if ye from your hearts aforgive not every one his brother their trespasses."
In conclusion, there may be a deeper, Atonement-rooted explanation for the requirement that we must forgive in order to be forgiven. That explanation might be found in the second work-around I've articulated here, though it might not derive from either work-around.