Ephesians 2:19-20 Ephesians 4:11-14 Matthew 24:9 1 Nephi 11:32-34 2 Nephi 27:5 Isaiah 24:5 1 Nephi 13:26-40 3 John 1:9-10 2 Timothy 4:3-4 Doctrine and Covenants 123:12
"The Church of Jesus Christ is built on the foundation of apostles and prophets. These leaders have divine priesthood authority. Through revelation they direct the affairs of the church. They maintain doctrinal purity, authorize the administration of ordinances, and call and confer upon others the priesthood authority.
"People rejected and killed Jesus Christ and the Apostles. With the death of the Apostles, the presiding priesthood authority was absent from the church. Consequently, there was no longer authority to confer the Holy Ghost or perform other saving ordinances. Revelation ceased, and doctrine became corrupted.
"Even before the death of the Apostles, many conflicts concerning doctrine arose. The Roman Empire, which at first had persecuted the Christians, later adopted Christianity. Important religious questions were settled by councils. The simple doctrines and ordinances taught by the Savior were debated and changed to conform to worldly philosophies. They physically changed the scriptures, removing plain and precious doctrines from them. They created creeds, or statements of belief, based on false and changed doctrine. Because of pride, some aspired to positions of influence. People accepted these false ideas and gave honor to false teachers who taught pleasing doctrines rather than divine truth.
"Throughout history, many people have sincerely believed false creeds and doctrines. They have worshiped according to the light they possessed and have received answers to their prayers. Yet they are 'kept from the truth because they know not where to find it.'
"Therefore, a restoration, not a reformation, was required. Priesthood authority did not continue in an unbroken line of succession from the Apostle Peter. To reform is to change what already exists; to restore is to bring back something in its original form. Thus, restoration of priesthood authority through divine messengers was the only possible way to overcome the Great Apostasy."
From Preach My Gospel, p. 36. Emphasis added.