For the benefit of my readers who are unfamiliar with the LDS church and it's basic beliefs, I will detail the Mormon church and tell their story the way they would tell it.
The Mormon story begins in 1820 when Joseph Smith, a boy of 14 who is confused about religion, retires into a grove of trees near his home. His intent, to pray to god and ask which church is true and which he should join. According to the LDS church, God the Father and Jesus Christ appeared personally to the boy and instructed him that ALL of the churches were false and that he should join none of them.
A few years later, Joseph Smith is getting ready for bed when an angel suddenly appears in his room. This angel identifies himself as Moroni, an ancient American prophet. Moroni shows Joseph, in vision, where a sacred record is buried; a record that Moroni himself buried 2,000 earlier. Joseph Smith goes to the place the next day and sure enough, he finds the record engraved on plates of pure gold.
After a time, Joseph Smith is allowed by god to take the record. Using the Urim & Thummim, a device found with the plates, Joseph Smith begins translating the record into English. The record contains a story of a family that lived in Jerusalem in the year 600 B.C. The father of this family, Lehi, is a prophet who is warned by god to leave Jerusalem because it will soon be destroyed. Lehi takes his family and travels to the sea, where they build a ship and sail to ancient America. The record contains a history of their wars and prophesies for 1000 years.
When Joseph Smith completes his translation, the resulting "Book of Mormon" is first published in 1830 and the golden record is taken into heaven by Moroni. That same year, Joseph Smith formally organizes the Church of Jesus Christ of Latter-day Saints. Due to persecution inspired by the devil, the saints are forced to move from place to place until they eventually cross the country and end up in Salt Lake City, UT.
The LDS revere Joseph Smith as the prophet of the restoration. During the time of Christ, Christ organized a church, but that church eventually fell into apostasy and the real truth was lost. Although great reformers tried to bring it back, they could not do it completely without the authority from god. Joseph Smith restored the true church to the earth along with the priesthood, the holy authority to act in god's name. Because Joseph Smith restored the true church back to the earth, the founding of Mormonism is often called "The Restoration".
The Book of Mormon is viewed as scripture as literally as the Bible. Mormons use both the Bible and the Book of Mormon. By reading and praying, anyone can come to the conviction that the Book of Mormon is true, and therefore by default, the Mormon church is true.
Joseph Smith built temples and introduced all sorts of new doctrines, including baptisms for the dead, the endowment ceremony, and a concept of eternal families. Worthy family members could be "sealed" in the temple, thus carrying a family relationship beyond this life and into the eternities.
A central theme of the church is that of continual revelation. The LDS strongly believe that the prophet leads the church under the direct guidance of Jesus Christ Himself! Worthy LDS members believe that they have the continual companionship of the Holy Ghost, which is a guide and a warner in case of danger. It is only with them if they strictly follow all the rules and commandments set forth by the church.
Just as the LDS believe that their church is literally true, they also believe that anyone who leaves the church has been deceived by satan and will go to hell forever. A person like myself who says negative about the church is literally working for satan to tear down the true kingdom of god.
The privilege of belonging to the Lord's only true church does not come cheap. Members are given many rules to follow and many commandments to fulfill. Mormonism provides much for it's members to do...
Temple attendance. But before a member can attend the temple he or she must pass two "worthiness" interviews. They are asked if they obey all the commandments. Do they pay an honest tithing? Do they believe in the church and follow the leaders? Do they live the Word of Wisdom? Are they sexually moral? Members who are renewing their recommend are also asked additional questions, such as, "Do you wear your garments 24/7 as directed?" and "Do you obey all the covenants you have previously made in the temple?" A negative answer to any of these questions will result in their temple recommend being denied.
In the temple, sacred ordinances are carried out which are necessary for salvation. The first time a person goes, he or she receives these ordinances for themselves. With each subsequent visit, they preform the ordinance on behalf of a deceased person who never got the chance during their lifetime. Mormons believe that before the end of the world, they will baptize and perform these sacred ordinances for every single person who has ever lived on the earth! Of course, the deceased will have the choice as to whether or not to accept those ordinances.
Once a person goes to the temple, they wear garments for the rest of their lives. They are even buried in garments and temple clothing when they die. Garments are a special underwear with markings in them. These markings help remind the wearer of the covenants they have made with god.
Tithing. Members are expected to pay 10% of their gross income to the church. Paying faithfully will bring you blessings, whereas not paying will bring you damnation. Paying a full tithing is definitely a requirement in order to get a temple recommend. It is considered a sin to not pay in full.
Home and visiting teaching. Men home teach and women visit teach. This is where a "home teacher" and his companion make monthly visits to a few assigned families. The purpose of the visit is to share a spiritual message and see to it that the family is living the gospel. Any abnormality is reported to the bishop. Home teaching is a biggie. While there is no direct discipline for not doing it, not doing it is strongly looked down upon.
Callings. All of the Mormon activities that take place at the local level are done completely by volunteer. Members of the ward or congregation are assigned a calling which may include: bishop, bishop's assistants, sunday school teacher, janitor, organist, etc. All positions are fulfilled by members of the ward. It is strongly discouraged to refuse a calling, as it has been extended by Jesus Christ Himself! Faithful fulfillment of one's individual calling is required in order to have a temple recommend.
Church meetings. A normal LDS church service lasts for three hours. There is a sacrament meeting, then sunday school, and then priesthood or relief society; priesthood for the men and relief society for the women. Regular church attendance is required in order to have a temple recommend.
Word of Wisdom. A health code of conduct set in place by Joseph Smith that directs the LDS to abstain from hot drinks, alcohol, and tobacco (the modern church has also included the use of illegal drugs). They are also directed to use meats sparingly. Word of Wisdom compliance is necessary for a temple recommend as well as baptism into the church.
Sexuality. Called the Law of Chastity, sexual activity is restricted ONLY to a married couple between themselves. Any other form of sexual activity is strictly forbidden, including masturbation, viewing of porn or other arousing stimulus, making out with and/or touching the private areas of a non-spouse (which they call "petting"), and even sexual thoughts. A person involved in any type of sexual activity other than intercourse with their legal husband or wife is involved in a serious sin. In fact, murder is the only sin that is more serious than sexual sin. Compliance with the Law of Chastity is definitely a requirement for a temple recommend.
Testimony. Each member is charged with gaining their own personal testimony of the church. It is common to hear people say, "I know the church is true" and they sometimes add, "with every fiber of my being." A testimony is a persons personal conviction that the church is true. It is stronger than any evidence or any criticism. This knowledge can only be given by the Holy Ghost, who, as before mentioned, can only witness of truth as long as the person completely complies with the church. Therefore, in order to have a true testimony, one needs to fully comply with ALL the guidelines of the church. Follow the prophet and do not doubt. Members will often share their testimony in order to convince their family and friends to join the church.
Once a month, on the first sunday of each month, Mormons have what they call Fast and Testimony meeting. During sacrament meeting, no lessons or sermons are taught, but the members take turns voluntarially sharing their testimonies and personal experiences. Even young, young children who can barely talk will share their testimony. "I'd like to bury my testimony. I know the church is twue." (As opposed to "I'd like to bear my testimony...")
Children are taught at a very young age to have a testimony. Boys are instructed that when they turn 19, they will serve a full time, two year mission for the church, where they will devote 100% of their time to finding new members. Young men are STRONGLY encouraged to serve and young women are STRONGLY encouraged to only date and marry a returned missionary. If a Mormon boy decides not to serve, it is very much looked down upon. Young men are under TREMENDOUS pressure to serve a mission. Young women can also serve if they wish but they are not under pressure like the boys are.
Follow the LDS church leaders and you will never go astray. They have the only truth and the only way to make it safely and happily through this mortal life. Only Mormons are truly happy. They have the restored truth and it is their holy mission and calling to share it with everyone. In fact, if you do not share the gospel with everyone, you will be accountable for their sins!
As you can see, life in the Mormon church is full of demands and expectations. Only by 100% compliance can you be saved. That is the life of a Mormon. While this post generalizes the Mormon religion and it's beliefs, it goes much, much deeper, which only a Mormon or a former Mormon can possibly comprehend. It is the truth and it is the only way. If you don't comply 100% you will be damned forever. If you do comply, you will be able to live in bliss with your worthy family members for the rest of forever. Hense the term, "Families Are Forever."
I hope this post has helped with your basic understanding of the Mormon church, how it came to be, and what is expected of the members. It definitely is brief and only lightly touches on the main points, but will give you a fairly good idea of who they are and what they believe.