In the Church of Jesus Christ of Latter-day Saints, we fast for many reasons although before I list those, I would like to discuss how fasting is done. Typically, a proper fast is a period of twenty four hours where a person abstains from the consumption of food and drink of any kind. In addition to this abstinence, members of the Church are encouraged to donate a fast offering which is a monetary donation used by the church to aid the poor and needy. With over 12 million members in the Church of Jesus Christ of Latter-day Saints, these fast offering donations can be quite effective. The Church encourages its members to fast at least once a month, on the first Sunday of each month. This corresponds to the schedule for Fast and Testimony meetings. Let it be understood though, that members are not limited to fasting only once a month. In fact, as we will see, we are encouraged to fast for a variety of reasons at any time.
You may notice, as I mention these things, that fasting is very similar to prayer in its purposes. This is because fasting is often used to strengthen the power of our prayers, and as we use the two of them together effectively, we will become much more effective in accomplishing the purposes that I will now mention.
The first is gratitude. We all know that prayer is one of the most common mediums by which we can thank God for all that He's given us. The Book of Mormon contains a story about the wars between two of the major civilizations on the American continent namely, the Nephites and Lamanites. In one battle, the Nephites (the good guys) are drastically out-numbered, but the Lord helps them and saves them from their enemies. In Alma 45:1, Alma tells us about how they responded when they received such help from the Lord. "Behold, now it came to pass that the people of Nephi were exceedingly rejoiced, because the Lord had again delivered them out of the hands of their enemies; therefore they gave thanks unto the Lord their God; yea, and they did fast much and pray much, and they did worship God with exceedingly great joy." These people saw the hand of the Lord in their victory, and gave him all the credit for it. In this way, fasting is an exercise of humility.
The next purpose for fasting is centered in our own personal desires. When we want something, or need something, usually we get on our knees and beg for it from the Lord in prayer. This is fabulous, but we can be more effective in that effort by simply beginning a fast and praying several times during that fast. How does that work? Its effects are two-fold. 1) By fasting, we enable ourselves to be closer to the Spirit. When that happens, we can understand the will of the Lord better and we will in turn pray for Him to do whta is best according to His marvelous plan. Everything will be accomplished according to His perfect wisdom, and in His own time. 2) Sacrifice brings blessings. As we give up food and drink for a period of time to show our desire for the Lord's help, it's almost like we are showing God that we are willing to give up whatever is necessary to just obtain that help. The Lord is pleased when He sees His children put such reliance and trust in Him. That is when He is most likely to grant the desire of our hearts. I hope that we will make an effort to be sure that those are righteous desires that are motivating our fast.
Perhaps the best reason to fast is the one I will now discuss: Truth. Everyone needs to know what is true and what's not. It is crucial that each of us know that Joseph Smith was a prophet of God, because if he was then we can be sure that we are following the one correct path which leads back to God. If he wasn't then w eneed to go find that path elsewhere. We need to have a testimony of the truth of many other things as well, such as the Plan of Salvation, the nature of God, and the power and purpose of the Atonement of Christ. Such truth is obtained by prayer and fasting. That's how Alma obtained his testimony. While preaching to the people throughout the land, he described. "(44) For I am called to speak after this manner, according to the holy order of God, which is in Christ Jesus; yea, I am commanded to stand and testify unto this people the things which have been spoken by our fathers concerning the things which are to come. (45) And this is not all. Do ye not suppose that I know of these things myself? Behold, I testify unto you that I do know that these things whereof I have spoken are true. And how do ye suppose that I know of their surety? (46) Behold, I say unto you they are made known unto me by the Holy Spirit of God. Behold, I have fasted and prayed many days that I might know these things of myself. And now I do know of myself that they are true; for the Lord God hath made them manifest unto me by his Holy Spirit; and this is the spirit of revelation which is in me" (Alma 5:44-46). He then goes on giving an extended testimony about the Atonement of Christ, making up one of my favorite chapters in the Book of Mormon.
What am I trying to say with all this? If you have not yet obtained a testimony of the truth of the things that I mentioned, then I suggest you fast and pray. As with Alma, it may take many days because the Lord makes us work for things. We do not receive that witness until after the trial of our faith (Ether 12:6), but we do receive it inasmuch as we are willing to do what is necessary to obtain it. I too have fasted and prayed very much to come to know the things that I know. The Book of Mormon also teaches us that somebody who does have this knowledge of truth (that we each need to have) can fast and pray for those who haven't yet obtained this knowledge (Alma 6:6). This is an act of missionary work, and we are all responsible to take part in this effort. Let us do so.
Another purpose that can be accomplished through fasting is repentance and forgiveness of sin. God will sanctify us from sin as we humble ourselves and try to become stronger in our faith. This is a fundamental principle of the gospel. God forgives the person who acknowledges his weaknesses and mistakes before Him in a humble, apologetic manner. Helaman teaches this principle quite well in Helaman 3:35. "Nevertheless they did fast and pray oft, and did wax stronger and stronger in their humility, and firmer and firmer in the faith of Christ, unto the filling their souls with joy and consolation, yea, even to the purifying and the sancitification of their hearts, which sanctification cometh because of their yielding their hearts unto God." Brothers and Sisters, repentance is one of the first principles of the gospel. If we want to truly repent with sincerity from our heart, we can fast to show the Lord how much we desire his forgiveness. Through fasting and prayer we can be forgiven and once again enjoyt the peace of mind and peace of conscience that comes when you know the Lord has forgiven you.
In connection with this thought, I should also mention that fasting helps us to overcome temptation. Even after we've fully repented of a sin, Satan will try to catch us in a moment where we don't expect it. But if we want God to give us strength, and help us to know and remember to do what is right, then we can fast and request it from Him. The First Presidency has said, "If you have a weakness or a sin that you have struggled to overcome, you may need to fast and pray in order to receive the help or forgiveness you desire. " I might also point out that fasting can give you the strength to overcome the temptation partly because it's an exercise of self-mastery. When you fast, you want food. You're hungry, but you try to focus your thoughts on spiritual things, and put your desire to eat away. Similarly, when we are tempted with inappropriate thoughts, or other spiritually dangerous situations, we can put those things aside and grasp onto appropriate, uplifting, spiritual things. We will train ourselves to choose the right in this way.
In conclusion, if you want to express gratitutude, live closer to the Spirit, call upon the Lord with more power, receive a testimony for yourself, or help another person to receive a testimony, be forgiven of your sins, and learn to avoid giving into temptation - I suggest you fast. Through my fasting and prayer, the Lord has granted me knowledge that Joseph Smith was a true prophet. He was God's instrument in restoring the one true Church to the earth so that we, God's children, can have the chance to fulfill the ordinances of the Gospel and eventually return to live with Him someday. I know that the Priesthood, which is the power God has given to man to act in His name, has been restored to the earth. I know that only by this authority can we take steps toward Heavenly Father's eternal kingdom. I know that Gordon B. Hinckley is a prophet of God for us today, and I surely know that the Church of Jesus Christ of Latter-day Saints is the only true and living church on the whole earth. I have a testimony of prayer and fasting, and I know that it works. I leave this with you in the name of Jesus Christ, amen.