One of our witnessing tactics is to find articles on churchofjesuschrist.org to discuss with Mormons. We encourage you to do this only after you have had a few discussions with them. Then they won’t be surprised by your going to their website. In fact, they probably will be pleasantly surprised you did. Sometimes, they will even suggest an article for you to look up.
One helpful article is chapter 4 of the Teachings of Spencer W. Kimball. It is entitled “The Miracle of Forgiveness”. It is available for download here.
The main reason to cite this chapter is to show the impossible demands of official Mormonism in connection with repentance and forgiveness. It will be important to highlight that these are the words of one of their prophets—words they can’t ignore. You will also need to be alert to their trying to water down these words by talking about “trying” etc. You might have to ask them repeatedly to show you where Kimball uses the word “try.” Always bring them back to what he said—not what they say.
There are a number of quotes which illustrate those impossible demands. Kimball’s entire point is that forgiveness is only achieved after a long and difficult process. He says it no more bluntly than the last paragraph in the section entitled, “Recognition of sin and feeling godly sorrow are a part of true repentance.” It says:
“To every forgiveness there is a condition. The plaster must be as wide as the sore. The fasting, the prayers, the humility must be equal to or greater than the sin. There must be a broken heart and a contrite spirit. There must be ‘sackcloth and ashes.’ There must be tears and genuine change of heart.”
Especially note the third sentence: “The fasting, the prayers, the humility must be equal to or greater than the sin.” This, however, wasn’t what the prophet Samuel told David. He simple said:
The Lord has taken away your sin.
2 Samuel 12:13
The next section of Kimball’s article, “Abandonment of sin includes building a new life” is especially helpful. There he repeatedly talks about abandoning and forsaking the sin. He also emphasizes that “effort is required, and not merely desire.” He also says: “the saving power does not extend to him who merely wants to change his life.” Both of those quotes are extremely helpful because, as stated above, most Mormons try to weaken the statements about abandoning the sin with the word “try.” They argue that we are to try to abandon the sin, but we don’t have to actually do so. Kimball, one of their prophets, disagrees. Use these sentences to hold their feet to the fire. Don’t let them off the hook with the word “try.”
Another striking sentence is the one immediately before the section, “True repentance includes a commitment to live the Lord’s commandments.” Kimball says: “The Lord will not forgive us unless our hearts are fully purged of all hate, bitterness and accusation against our fellowmen.” Note the word “fully.” What person can honestly say they are harboring no bitterness or accusation against anybody?
One final paragraph which emphasizes how strongly Kimball emphasized human effort is in the middle of the last section. There he states:
“Repentance must involve an all-out, total surrender to the program of the Lord. That transgressor is not fully repentant who neglects his tithing, misses his meetings, breaks the Sabbath, fails in his family prayers, does not sustain the authorities of the Church, breaks the Word of Wisdom, does not love the Lord nor his fellowmen. … God cannot forgive unless the transgressor shows a true repentance which spreads to all areas of his life. …”
Consider the last sentence: “God cannot forgive unless the transgressor shows a true repentance which spreads to all areas of his life.” Have them wrestle with this. Don’t overlook the thought of true repentance. True repentance is the repentance explained in the article including abandonment of sin. In other words, God doesn’t forgive somebody unless they abandon sin in all areas of their life!
As stated above, the main reason to refer to Kimball’s article is to highlight how difficult LDS repentance and forgiveness is. This is what you will want to emphasize. You can also, however. contrast the wonderful forgiveness you have based not on your abandonment of sin, but on Jesus’ complete obedience to God.