Joseph Fielding Smith
"In quoting the words of Malachi to Joseph Smith the Angel Moroni also said that these words were shortly to be fulfilled: (quotes Malachi 3:2-5).
"In believing that this has reference to the second coming of Christ the Latter-day Saints stand in a peculiar position among all people, for it is the general belief that this had fulfilment in the first coming of Christ. If we investigate the matter, however, it is made very clear that in the days of the ministry of the Redeemer of the world, he did not come in judgment and to purify in the crucible so that all dross should be destroyed. In that day he was abused and persecuted and denied by men. The widow and the fatherless were not given justice against those who oppressed them. Sorcerers and adulterers were not punished, and all men were able to abide that day,
"But, when Christ comes the second time it will be in the clouds of heaven, and it shall be the day of vengeance against the ungodly, when those who have loved wickedness and have been guilty of transgression and rebellion against the laws of God will be destroyed. All during the ministry of Christ wickedness ruled and seemed to prevail, but when he comes in the clouds of glory as it is declared in this message of Malachi to the world, and which was said by Moroni to be near at hand, then Christ will appear as the refiner and purifier of both man and beast and all that pertains to this earth, for the earth itself shall undergo a change and receive its former paradisiacal glory." (Doctrines of Salvation, 3:10-11)