The distinguishing characteristic of having one’s calling and election sure is the promise of eternal life. The Lord hereby gives Alma his calling and election. Notice that this promise of eternal life comes after Alma had shown the Lord that his faith was unfailing and his diligence was undaunted. Such a grand promise from the Lord comes only after ’the Lord has thoroughly proved him, and finds that the man is determined to serve Him at all hazards’ (Teachings, p. 150). Alma had already demonstrated this determination.
This doctrine is sacred and discretion should be used regarding the appropriate time and audience in discussing it, but Peter thought it important enough for the saints that he exhorted them to make their calling and election sure, saying, brethren, give diligence to make your calling and election sure (1 Pet 1:10). If one is to make their calling and election sure, it is helpful to understand what this phrase means. Elder McConkie explains.
Bruce R. McConkie
"Those members of the Church who devote themselves wholly to righteousness, living by every word that proceedeth forth from the mouth of God, make their calling and election sure. That is, they receive the more sure word of prophecy, which means that the Lord seals their exaltation upon them while they are yet in this life. Peter summarized the course of righteousness which the saints must pursue to make their calling and election sure and then (referring to his experience on the Mount of Transfiguration with James and John) said that those three had received this more sure word of prophecy. (2 Pet. 1.)
"Joseph Smith taught: ’After a person has faith in Christ, repents of his sins, and is baptized for the remission of his sins and receives the Holy Ghost (by the laying on of hands), which is the first Comforter, then let him continue to humble himself before God, hungering and thirsting after righteousness, and living by every word of God, and the Lord will soon say unto him, Son, thou shall be exalted. When the Lord has thoroughly proved him, and finds that the man is determined to serve him at all hazards, then the man will find his calling and election made sure, then it will be his privilege to receive the other Comforter.’ To receive the other Comforter is to have Christ appear to him and to see the visions of eternity. (Teachings, pp. 149-151.)
"Thus, as the prophet also said, ‘The more sure word of prophecy means a man’s knowing that he is sealed up unto eternal life, by revelation and the spirit of prophecy through the power of the Holy Priesthood.’ (D. & C. 131:5.) Those so favored of the Lord are sealed up against all manner of sin and blasphemy except the blasphemy against the Holy Ghost and the shedding of innocent blood. That is, their exaltation is assured; their calling and election is made sure, because they have obeyed the fulness of God’s laws and have overcome the world. Though such persons ’shall commit any sin or transgression of the new and everlasting covenant whatever and all manner of blasphemies, and if they commit no murder wherein they shed innocent blood, yet they shall come forth in the first resurrection, and enter into their exaltation.’ (D. & C. 132:26.)
“The Lord says to them: ’Ye shall come forth in the first resurrection; … and shall inherit thrones, kingdoms, principalities, and powers, dominions, all heights and depths.’ (D. & C. 132:19.) The prophet, for one, had this seal placed upon him. That is, he knew ’by revelation and the spirit of prophecy, through the power of the Holy Priesthood,’ that he would attain godhood in the world to come. To him Deity said: ’I am the Lord thy God, and will be with thee even unto the end of the world, and through all eternity; for verily I seal upon you your exaltation, and prepare a throne for you in the kingdom of my Father with Abraham your father.’ (D. & C. 132:49.)” (Mormon Doctrine, pp. 109-110)