3 Nephi 27

The Savior teaches again His gospel  and suggesting in my mind the purpose of being pure, clean, and unspotted saying -

"...this is the gospel which I have given unto you—that I came into the world to do the will of my Father, because my Father sent me.
14 And my Father sent me that I might be lifted up upon the cross; and after that I had been lifted up upon the cross, that I might draw all men unto me, that as I have been lifted up by men even so should men be lifted up by the Father, to stand before me, to be judged of their works, whether they be good or whether they be evil—
15 And for this cause have I been lifted up; therefore, according to the power of the Father I will draw all men unto me, that they may be judged according to their works.
16 And it shall come to pass, that whoso repenteth and is baptized in my name shall be filled; and if he endureth to the end, behold, him will I hold guiltless before my Father at that day when I shall stand to judge the world."  (Book of Mormon | 3 Nephi 27:13 - 16)

For -

"...no unclean thing can enter into his kingdom; therefore nothing entereth into his rest save it be those who have washed their garments in my blood, because of their faith, and the repentance of all their sins, and their faithfulness unto the end.
20 Now this is the commandment: Repent, all ye ends of the earth, and come unto me and be baptized in my name, that ye may be sanctified by the reception of the Holy Ghost, that ye may stand spotless before me at the last day."  (Book of Mormon | 3 Nephi 27:19 - 20)

I specifically note - clean and spotless are the requirements of entering into the kingdom of God.  Thus -

"...that thou mayest more fully keep thyself unspotted from the world, thou shalt go to the house of prayer and offer up thy sacraments upon my holy day..."  (Doctrine and Covenants | Section 59:9)