30 And I said unto them that our father also saw that the justice of God did also divide the wicked from the righteous; and the brightness thereof was like unto the brightness of a flaming fire, which ascendeth up unto God forever and ever, and hath no end.
The gulf of filthy water is not the only thing separating the wicked from the righteous. The justice of God referred to by Nephi also separates the two. This seems obvious on the surface, but it might be helpful to explore the nature of justice.
Justice appears to be the “default setting” of our lives, both mortal and eternal. Another term for justice might be “natural consequences.” In other words, every time we make a choice to do something, to act a certain way, there are natural consequences to that behavior or action. That is even found in the laws of physics: “for every action there is an equal and opposite reaction.” Justice appears to be a law that cannot be broken, at least not without dire consequences (there it is again: action consequence).
There are some laws that can’t be broken at all. These are physical laws, such as the law of gravity, which have no specific moral implications attached to them. They just are, and there’s nothing we can do about it. And the thing about these natural or physical laws is that we don’t even need to understand them to be subject to them. We don’t understand how gravity works; yet we all must obey this law of nature. We can’t help it.
Apparently there is another kind of law that, technically speaking, can be broken, but not without life and/or status-changing consequences. Moral consequences. Justice seems to fall into this category. The law of justice says that when we break a commandment, we must be punished. When we keep a commandment, we are blessed. “There is a law, irrevocably decreed in heaven before the foundations of this world, upon which all blessings [and punishments] are predicated—and when we obtain any blessing [or punishment] from God, it is by obedience [or disobedience] to that law upon which it is predicated” (D&C 130:20–21 emphasis and comments added). It only makes sense that if this scripture is true, then it’s opposite is also true.
Our heavenly Father must also keep certain laws in order to retain the status of godhood. And He has no leeway to make mistakes. He must be perfectly predictable in how He deals with His children (see Mormon 9:19). If God were to ignore the law of justice, He would forfeit His godhood (Alma 42:22 (19–28)).
So this justice that divides the wicked from the righteous is there because of an eternal law: the Law of Justice. If God were to remove that gulf of division, he would cease to be God. The Atonement is the only way that our loving Heavenly Father (who does not want us to be hurt by the Law of Justice) could offer us mercy for the things we do wrong, and not break the Law of Justice. He wants to spare us as much of the pain of sin as possible, yet the price for sin must be paid in full. The only answer: have someone else pay the price.