While Mormons are often thought to be soft on Grace, it is traditional Christianity, not Latter-day Saints, that sets limits on the power of the Atonement of Christ.
It is one thing to believe that through Christ we can be cleansed from our sins and made to dwell eternally in worshipful awe of The Divine. But to believe that we can become like our Father in Heaven requires a categorically different perspective on Grace.
Only an infinite Atonement could bridge the infinite gulf between who we are now and who we may become. There is no penance mortals can pay to satisfy Justice. A stone would have an easier time willing itself to become the Pietà without the hand of a sculptor.
But what about all that Mormon talk about works? A Book of Mormon prophet, Abinadi, illuminates the subject. He was speaking with a group of corrupted priests and explained the usefulness and the limitations of obeying the law of Moses:
Doth salvation come by the law of Moses? What say ye? And they answered and said that salvation did come by the law of Moses. But now Abinadi said unto them: I know if ye keep the commandments of God ye shall be saved; yea, if ye keep the commandments which the Lord delivered unto Moses in the mount Sinai….And now ye have said that salvation cometh by the law of Moses. I say unto you that it is expedient that ye should keep the law of Moses as yet; but I say unto you that salvation doth not come by the law alone; and were it not for the atonement, which God himself shall make for the sins and iniquities of his people, that they must unavoidably perish, notwithstanding the law of Moses.
There are conditions for Grace to be sure, and even the most ardent evangelical believes that Faith, at least, is requisite. But the conditions are not a co-pay; they add no credit to a celestial balance sheet. We believe in repentance and keeping the commandments, but neither of these do anything to overcome sin and death, they do not earn us salvation, because without Christ all is vain.
“I say unto you, my bretheren,” said King Mosiah to his people,
that if you should render all the thanks and praise which your whole soul has power to possess, to that God who has created you… I say unto you that if ye should serve him who has created you from the beginning…if ye should serve him with all your whole souls yet ye would be unprofitable servants. And behold, all that he requires is to keep his commandments.”
To carry on the financial metaphor, we are never in the black. Nothing we do shrinks the debt. Christ paid every senine. But the conditions of repentance and commandment keeping are necessary to receive The Heavenly Gift.