To see just how good a Mormon must be to be right with God let’s go directly to the LDS scriptures and prophets.
“For I the Lord cannot look upon sin with the least degree of allowance; Nevertheless, he that repents and does the commandments of the Lord shall be forgiven; And he that repents not, from him shall be taken even the light which he has received; for my Spirit shall not always strive with man, saith the Lord of Hosts.” (Doctrine and Covenants 1:31-33)
According to D&C 1:31-33, what degree of sin can God look upon?
"Behold, he who has repented of his sins, the same is forgiven, and I, the Lord, remember them no more. By this ye may know if a man repenteth of his sins--behold, he will confess them and forsake them." (Doctrine and Covenants 58:42-43)
Have you forsaken all of your sins?
“There is one crucial test of repentance. This is abandonment of the sin… In other words, it is not real repentance until one has abandoned the error of his ways and started on a new path.” (The Miracle of Forgiveness by Spencer Kimball, p.163)
Have you really repented and thus abandoned your sin?
"…unto that soul who sinneth shall the former sins return, saith the Lord your God." (Doctrine and Covenants 82:7)
According to D&C 82:7, what happens to you if you do sin again?
“The Lord cannot save men in their sins but only from their sins, and that only when they have shown true repentance.” (The Miracle of Forgiveness by Spencer Kimball, p.166)
“The Lord will indeed forgive, but he will not tolerate repetitions of the sin:” (The Miracle of Forgiveness by Spencer Kimball, p.357; refers to Ether 2:15)
“An incomplete repentance never brought about complete forgiveness” (The Miracle of Forgiveness by Spencer Kimball, p.212)
“And I say unto you again that he cannot save them in their sins; for I cannot deny his word, and he hath said that no unclean thing can inherit the kingdom of heaven; therefore, how can ye be saved, except ye inherit the kingdom of heaven? Therefore, ye cannot be saved in your sins.” (Alma 11:37)
Can God save you? Yes, according to the Book of Mormon but, you cannot be saved in your sins. You can only be saved if you genuinely repent, which is to completely and permanently stop sinning.
“Discontinuance of sin must be permanent” (The Miracle of Forgiveness by Spencer Kimball, p.176)
It’s been said “I’ll try my best and God will make up for the rest.”
“Trying is not sufficient Nor is repentance complete when one merely tries to abandon sin…To ‘try’ is weak. To ‘do the best I can’ is not strong. We must always do better than we can.” (The Miracle of Forgiveness by Spencer Kimball, pp.164-165)
“And if ye shall deny yourselves of all ungodliness and love God with all your might, mind and strength, then his grace sufficient for you…” (Moroni 10:32)
According to Moroni 10:32, when does God make up for the rest (the times we‘ve fallen short)? When is God’s grace sufficient? Is it not after you’ve denied yourself “all” ungodliness? Have you denied yourself all ungodliness? Do you ever lie, lust, get angry without cause, commit any sin or do anything that is ungodly?
“Those who feel that they can sin and be forgiven and then return to sin and be forgiven again and again must straighten out their thinking. Each previously forgiven sin is added to the new one. Thus, when a man has made up his mind to change his life there must be no turning back.” (The Miracle of Forgiveness by Spencer Kimball, p.170)
“daily transgression and daily repentance is that which is not pleasing in the sight of God.” (Teachings of the Prophet Joseph Smith, p. 148)
“We can hardly be too forceful in reminding people that they cannot sin and be forgiven and then sin again and again and expect repeated forgiveness” (The Miracle of Forgiveness by Spencer Kimball, p.360)
"In the context of the spirit of forgiveness, one good brother asked me, "Yes, that is what ought to be done, but how do you do it? Doesn't that take a superman?' 'Yes,' I said, 'but we are commanded to be supermen. Said the Lord, 'Be ye therefore perfect, even as your Father which is in heaven is perfect.' (Matt. 5:48.) We are gods in embryo, and the Lord demands perfection of us.'" (The Miracle of Forgiveness by Spencer Kimball, p. 286)
God commands you to stop sinning and be perfect. Note, it says “be” perfect not “become” perfect.
“…for I know that the Lord giveth no commandments unto the children of men, save he shall prepare a way for them that they may accomplish the thing which he commandeth them.” (1 Nephi 3:7)
Does God give a command you can’t keep? Wouldn’t your best be sinless perfection?
“Being perfect means to triumph over sin. This is a mandate from the Lord. He is just and wise and kind. He would never require anything from his children which was not for their benefit and which was not attainable. Perfection therefore is an achievable goal." (The Miracle of Forgiveness by Spencer Kimball, p. 209)
“…for we know that it is by grace that we are saved, after all we can do.” (2 Nephi 25:23)
Are you doing “all” that you can do? Are you perfect? According to the prophet and the Book of Mormon you can be perfect. God commands perfection of you and you’ll only be saved by grace after you do all you can do. (2 Nephi 25:23)
You must stop sinning before death
“Men and women who live in mortality and who have heard the gospel here have had their day, their seventy years to put their lives in harmony, to perform the ordinances, to repent and to perfect their lives…spirit world repentance cannot recompense for that which could and should have been done on earth.” (The Miracle of Forgiveness by Spencer Kimball, pp.314-315)
“…this life is the time for men to prepare to meet God… For behold, if ye have procrastinated the day of your repentance even until death, behold, ye have become subjected to the spirit of the devil, and he doth seal you his; therefore, the Spirit of the Lord hath withdrawn from you, and hath no place in you, and the devil hath all power over you; and this is the final state of the wicked” (Alma 34:30-35, see also Mosiah 2:36-39; Alma 12:24; 2 Nephi 9:38)