I have heard that there are other churches called Latter-Day Saints, such as the Reorganized Church. Which one is the true church?
The Church of Jesus Christ of Latter-day Saints, commonly called the Mormon Church, was founded by the prophet Joseph Smith on April 6, 1830. In preparation for that founding, Joseph Smith, at age 14, was visited by the presence of both God, the Eternal Father and His Son, Jesus Christ, in one of the most marvelous and significant visions of the Almighty since the world began. The purpose of that visit was to restore again to the earth the gospel of Jesus Christ that had been lost through apostasy soon after the crucifixion of the Savior. In preparation for the restoration of the gospel, Joseph Smith and Oliver Cowdery, on the 15 day of May 1829 were visited by John the Baptist as a resurrected being, who laid his hands on their heads and ordained them to the Priesthood of Aaron, that has the rights to administer in the temporal affairs of the kingdom. Shortly thereafter, Peter, James and John, who held the presidency of the church following the death of the Savior, appeared to Joseph Smith, Oliver Cowdery and Sidney Rigdon, and laying their hands on their heads ordained them to the Melchizedek Priesthood, which holds all the keys of priesthood power delegated by God to man, giving them authority to organize the restoration of the Church of Jesus Christ to the earth again. As mentioned, this organization took place on April 6, 1830.
On 27 June, 1844, Joseph Smith and his brother Hyrum were assassinated by a mob in Carthage, Illinois. Following the assassination, Brigham Young, who at the time was the president of the Quorum of the Twelve Apostles, was called to be the president of the Church. He led the migration of the saints westward to settle the Salt Lake Valley and to develop Mormon communities and industry throughout the western United States.
Beginning with the death of the prophet, multiple schisms and splinter groups appeared, so that the present-day LDS Restoration movement consists of almost a hundred different faith groups. In answer to your question, we will concentrate on only one group, among the first to appear and the largest of the splinter groups. It was called the Reorganized Church of Jesus Christ of Latter-day Saints, and today is known as The Community of Christ. The proponents of this group held the belief that succession to the presidency of the Latter-day Saint, or Mormon Church, should follow a patriarchal line. However, the prophet’s oldest son, Joseph Smith III, was only 11 years old at the time of his father’s death, so the proponents of this belief held their organization in receivership until the young Joseph Smith became of age. Joseph Smith III initially refused the offer to lead the RLDS Church, but relented and became its first president in 1863. He was ordained as president by William Marks, Zenas Gurley, Samuel Powers, and W. W. Blair. It is vital in determining which church is the true church to investigate the authority by which these four individuals ordained the first president of the RLDS Church.
Following the martyrdom of Joseph Smith, William Marks joined an offshoot sect called the Strangites In 1852 he left the Strangites and joined with Charles B. Thompson in organizing a new church. He left that church in 1853 and by 1855 was associated with apostate John E. Page. On 11 June 1859 he was received into the Reorganized Church and was one of the four persons to ordain Joseph Smith III as its president on April 8, 1863.
Zenas Gurley joined The Church of Jesus Christ of Latter-day Saints in 1838 and held the office of seventy at the time of the martyrdom. He supported the Twelve Apostles until the time of the exodus from Nauvoo. He left the Church and joined with James J. Strang. Later he participated in organizing the RLDS Church.
Neither Samuel Powers nor W. W. Blair ever held the priesthood or membership in the Church established by the Lord through the Prophet Joseph Smith.
The answer to the question, which of these two organizations is the true church, could fill a book, but the issue is immediately settled merely by considering the authority by which each organization was formed. In the case of the Church of Jesus Christ of Latter-day Saints, the authorities were the resurrected beings, Peter, James and John. In the case of the Reorganized Church of Jesus Christ of Latter-day Saints, the organizing authority and the authority by which its first president was ordained was by two apostate members of the Church of Jesus Christ, and two individuals who had never held any priesthood authority.
If you follow the history of these two organizations you will find that the Church of Jesus Christ of Latter-day Saints has continued to this day with the same organization, the same priesthood, and the same doctrine that it had at the beginning, whereas the Reorganized Church has changed its name, its doctrine, its organization and its belief system.
So the Church of Jesus Christ of Latter-day Saints continues as God’s kingdom on the earth, with a current membership of over 15 million people in countries all over the world, blessing the lives of countless millions under the specific direction of the Lord Jesus Christ, through his servants who preside over the Church as prophets, seers and revelators.