The justice of God demands that every time a law of God is violated, there is a punishment for the transgression. Since God’s children are the ones transgressing His laws, justice demands that they pay the appropriate price. However, the mercy of God has allowed an intercessor. The price would still have to be paid, but an allowance would be made such that the price could be paid by someone else. The only individual who met the qualifications needed to act as an intercessor was Jesus Christ. Thus, as our Savior and Redeemer, he answers the ends of the law; he pays the price, he makes sure the irrevocable decrees of a just God are fulfilled, and thereby satisfies the demands of justice.
And thus he shall bring salvation to all those who shall believe on his name; this being the intent of this last sacrifice, to bring about the bowels of mercy, which overpowereth justice, and bringeth about means unto men that they may have faith unto repentance.
And thus mercy can satisfy the demands of justice, and encircles them in the arms of safety, while he that exercises no faith unto repentance is exposed to the whole law of the demands of justice; therefore only unto him that has faith unto repentance is brought about the great and eternal plan of redemption. (Alma 34:15-16)
Boyd K. Packer
"Each of us, lives on a kind of spiritual credit. One day the account will be closed, a settlement demanded. However casually we may view it now, when that day comes and the foreclosure is imminent, we will look around in restless agony for someone, anyone, to help us....
"Unless there is a mediator, unless we have a friend, the full weight of justice untempered, unsympathetic, must, positively must, fall on us. The full recompense for every transgression, however minor or however deep, will be exacted from us to the uttermost farthing.
"But know this: Truth, glorious truth, proclaims there is such a Mediator. ’For there is one God, and one mediator between God and men, the man Christ Jesus.’ (1 Timothy 2:5.) Through Him mercy can be fully extended to each of us without offending the eternal law of justice. This truth is the very root of Christian doctrine. You may know much about the gospel as it branches out from there, but if you only know the branches and those branches do not touch that root, if they have been cut free from that truth, there will be no life nor substance nor redemption in them.
“The extension of mercy will not be automatic. It will be through covenant with Him. It will be on His terms, His generous terms, which include, as an absolute essential, baptism by immersion for the remission of sins. All mankind can be protected by the law of justice, and at once each of us individually may be extended the redeeming and healing blessing of mercy. (CR, April 1977, p. 80.)” (McConkie and Millet, Doctrinal Commentary on the Book of Mormon, vol. 2, pp. 233-4)
Hugh Nibley
“…having redeemed them, and satisfied the demands of justice. Then he says, Now can I get them through?…So he goes ahead as our sponsor and clears the legal difficulties. There is serious doubt about whether our admission is really justified, so he generously intercedes for us. He breaks the barrier, and then he faces the problem of our legal right to go on. Do we deserve it? No. His argument on our behalf is for mercy and compassion.” (Teachings of the Book of Mormon, Lecture 35, p. 85)