The LDS church was founded on the very premise that a total or complete apostasy occurred very early on in the church and there was no true church in earth until it was reestablished by Joseph Smith in 1830. All Mormons must believe this in order to justify a need for their church. In fact B.H Roberts an LDS Seventy wrote in the “History of the Church” that, “Nothing less than a complete apostasy from the Christian religion would warrant the establishment of the Church of Jesus Christ of Latter-day-Saints” (vol. 1:XL). If this is the case, then the D&C and BOM are false.
John 21 (KJV) states the following:
 Then Peter, turning about, seeth the disciple whom Jesus loved following; which also leaned on his breast at supper, and said, Lord, which is he that betrayeth thee?
 Peter seeing him saith to Jesus, Lord, and what shall this man do?
 Jesus saith unto him, If I will that he tarry till I come, what is that to thee? follow thou me.
 Then went this saying abroad among the brethren, that that disciple should not die: yet Jesus said not unto him, He shall not die; but, If I will that he tarry till I come, what is that to thee?
Now what most logical people would see as a mild correction from Jesus to Peter, Joseph Smith misinterpreted as being a promise from Jesus that John the Apostle would never experience earthly death. In fact Joseph Smith went so far as to claim that John walked up to him one day in Pennsylvania in 1829 and handed him a testimony to this:
DOCTRINE AND COVENANTS
OF THE CHURCH OF JESUS CHRIST OF LATTER-DAY SAINTS
Revelation given to Joseph Smith the Prophet and Oliver Cowdery, at Harmony, Pennsylvania, April 1829, when they inquired through the Urim and Thummim as to whether John, the beloved disciple, tarried in the flesh or had died. The revelation is a translated version of the record made on parchment by John and hidden up by himself. HC 1: 35–36.
1–3, John the Beloved shall live until the Lord comes; 4–8, Peter, James, and John hold gospel keys.
1 AND the Lord said unto me: John, my beloved, what bdesirest thou? **For if you shall ask what you will, it shall be granted unto you. **
2 And I said unto him: Lord, give unto me apower over death, that I may live and bring souls unto thee. **
3 And the Lord said unto me: Verily, verily, I say unto thee, because thou desirest this thou shalt tarry until I come in my glory, and shalt prophesy before nations, kindreds, tongues and people. **
4 And for this cause the Lord said unto Peter: If I will that he tarry till I come, what is that to thee? For he desired of me that he might bring souls unto me, but thou desiredst that thou mightest speedily come unto me in my kingdom.
Furthermore, Third Nephi in the BOM states that the resurrected Jesus appeared to three Nephite disciples and promised them that hey would not experience earthly death:
7 Therefore, more blessed are ye, for ye shall never taste of death; but ye shall live to behold all the doings of the Father unto the children of men, even until all things shall be fulfilled according to the will of the Father, when I shall come in my glory with the powers of heaven.
8 And ye shall never endure the pains of death; but when I shall come in my glory ye shall be changed in the twinkling of an eye from mortality to immortality; and then shall ye be blessed in the kingdom of my Father.
9 And again, ye shall not have pain while ye shall dwell in the flesh, neither sorrow save it be for the sins of the world; and all this will I do because of the thing which ye have desired of me,** for ye have desired that ye might bring the souls of men unto me, while the world shall stand**.