What is faith?
The word 'faith' can be confusing, because it means different things to different people. Most people, when they use the word 'faith', they mean whatever group of beliefs that you have. You can have faith in a religion, such as Islam (for Muslims), Judaism (for Jews), or Christianity (for Christians). You can have faith in laws of nature or of science. You can even have faith in a wood carving that you made with your own hands. In this sense, faith is no different than belief.
The scriptures, however, and especially the Book of Mormon, give a very different meaning to the word. The Book of Mormon describes faith as a very real spiritual quality that gives power to whoever possesses it. The scriptures say that it can be grown and developed, just as you can plant a seed and care for it, and it will grow into a flower, or a vegetable, or even a mighty oak tree.
However, this only works if you develop faith in something real and true. It would do no good to have faith that, if you plant a small rock it will grow into an apple tree. That is not true, no matter how much you believe in it.
What do you have faith in?
In the spiritual sense, faith can only be developed and grown when it is centered upon God, specifically in Jesus Christ, the son of God. As King Benjamin told his people, "I say to you that there will be no other name given, or any other way or means, through which mankind can be saved, only in and through the name of Christ the Lord All-powerful." (Mosiah 1:16) Your faith can be in your parents to save you from hunger, or the Government to protect you. Your faith can be in science or religion to show you how things really are. Your faith can even be in becoming smarter, or more handsome, or more physically fit or beautiful or popular than others, in the belief that it will make you happy. You can even put your trust in a priest or prophet or church to lead you to salvation. All of these things will fail you, however. None of these things will last. There is only one name given that can save you from your fears, your doubts, and your unhappiness. That name is Jesus Christ. Therefore, if you wish to develop faith, it must be in Him and Him alone.
Why is faith important?
Joseph Smith called faith the "foundation of all righteousness". In other words, anyone who wants to be saved by God must begin with faith. The Apostle Paul wrote,"without faith it is impossible to please [God], for he that comes to God must believe that he is, and that he is a rewarder [or a revealer] to those who diligently [persistently] seek him." In other words, you could no more approach God and be saved without faith in Jesus Christ than you could breathe without air. It is the first principle and the foundation upon which you must build if you desire any heavenly blessing from God.
How does faith begin? (Alma 32)
Jesus taught that "The kingdom of heaven is like a grain of mustard seed which a man took and put in his field: Which is smaller than all seeds; but when it has come up it is greater than the plants, and becomes a tree, so that the birds of heaven come and make their resting-places in its branches." (Matthew 13:31 BBE)
Faith, when it begins, can be very small and very weak. Like a tiny mustard seed, which is no bigger than a grain of sand. It's very small and appears unimportant. It is easily overlooked and easily forgotten. However, if you plant it and take care of it, it will begin to grow. When you begin, you may not even believe yet. You may only wish or desire to believe. That is enough with which to begin. If you allow your faith to develop, it can grow from desire to belief, and then to faith and finally to a certainty or actual knowledge of God.
Belief can come from study and trusting others. Belief can be very weak, or it can be a strongly held conviction. However, it does not become faith until you act upon it. Faith is a principle of action and therefore it is required that you do something about your belief before it can become faith.
To begin, you must first hear the word of God. That is the seed. Plant that seed in your heart, or in other words, desire to believe and focus on that desire. Think about it, pray about it, and begin to live in obedience to the word of God. As you do, that seed will begin to sprout and grow within you. As Alma says, "it will begin to swell [or grow] within you" so that you will begin to say to yourself, this must be a good seed because it brings light to my understanding and it is delicious to me. This is how faith begins and how it continues to develop.
How is faith obtained? (By study and by faith)
Because of the things he taught, Joseph Smith had many enemies during his life. At one point, he was thrown into a dark, smelly dungeon for over four months. Those in charge of the prison would only give him dirty water and stale food to eat. One time, they tried to poison him. This was a terrible time in Joseph's life, but it was also a time when, because of his humble state, he received many revelations from God. During this time, he wrote a letter to members of the Church where he wrote, "the things of God are of deep import, and time, and experience, and careful and ponderous and solemn thoughts can only find them out. Your mind, O man, if you will lead a soul unto salvation, must stretch as high as the utmost Heavens, and search into and contemplate the lowest considerations of the darkest abyss, and expand upon the broad considerations of Eternal expanse. You must commune with God."
If I were to put it another way, I think Joseph is describing here the attitude you must have in order to find God and be saved. The way to God is not obvious or easy. Jesus said only few would find the way. It is not because God has hidden it from us, but it is because there are so few of us willing to take the time to think about it. The things of God require us to be humble (openly admitting that you don't know very much), and careful (treating the word of God with great care and respect), and ponderous (this means deep thinking) and solemnity (treating Godly things as sacred and serious things, not to be joked about or treated lightly). Only those who are willing to act in this manner, with patience (for it will take time) and persistence (for it will require experience) will find God. I don't believe true faith can be had in any other way.